diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3cd19e2..8904076 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,16 @@
 ## Changelog
 
+### 3.0.0 (Next)
+
+* Your contribution here.
+
+* [#111](https://github.com/ruby-grape/grape-active_model_serializers/pull/111): Apply explicit namespace roots consistently to single objects and collections, intentionally changing single-object response keys; document migration and preserve adapter behavior - [@dblock](https://github.com/dblock).
+
 ### 2.0.2 (Next)
 
 * Your contribution here.
 
+* [#107](https://github.com/ruby-grape/grape-active_model_serializers/pull/107): Honor namespace and `render` collection roots without changing inferred single-object roots; document adapter behavior, root precedence, and unwrapped arrays - [@dblock](https://github.com/dblock).
 * [#110](https://github.com/ruby-grape/grape-active_model_serializers/pull/110): Add SimpleCov LCOV reports, merged stable-matrix Coveralls reporting, and a coverage badge; remove the obsolete Code Climate badge and refresh gem/CI badge links - [@dblock](https://github.com/dblock).
 * [#109](https://github.com/ruby-grape/grape-active_model_serializers/pull/109): Document the optional third-party Swagger model parser, response model configuration, and schema limitations - [@dblock](https://github.com/dblock).
 * [#106](https://github.com/ruby-grape/grape-active_model_serializers/pull/106): Update default serializer options documentation to use AMS 0.10 field filtering and cover request-level defaults and overrides - [@dblock](https://github.com/dblock).
diff --git a/README.md b/README.md
index 2f30de4..c278e9a 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,7 @@
     - [Writing Serializers](#writing-serializers)
     - [Serializers are inferred by active_record model names](#serializers-are-inferred-by-active_record-model-names)
     - [Array Roots](#array-roots)
+    - [Single-Object Roots](#single-object-roots)
     - [API Versioning](#api-versioning)
     - [Manually specifying serializer / adapter options](#manually-specifying-serializer--adapter-options)
     - [Error Serialization](#error-serialization)
@@ -86,14 +87,22 @@ In this case, as User objects are being returned, grape-active_model_serializers
 
 ### Array Roots
 
-When serializing an array, the array root is set to the innermost namespace name if there is one, otherwise it is set to the route name.
+Root wrapping depends on the ActiveModelSerializers adapter. The default `:attributes` adapter ignores `root` and returns a bare array. Select the `:json` adapter to wrap the collection in a named root:
+
+```ruby
+ActiveModelSerializers.config.adapter = :json
+```
+
+Grape's `format :json` selects the response format, not the AMS adapter. The `:json_api` adapter follows JSON:API's `data` structure instead of using an arbitrary root.
+
+With the `:json` adapter, the default array root is the innermost namespace name if there is one, otherwise it is the route name.
 
 In the following API the array root is `users`.
 
 ```ruby
 namespace :users do
-  get ":id" do
-    @user = User.find(params[:id])
+  get '/' do
+    User.all
   end
 end
 ```
@@ -102,10 +111,60 @@ In the following example the array root is `people`.
 
 ```ruby
 get "people" do
-  @user = User.all
+  User.all
+end
+```
+
+Set `root` on a namespace or route to override the inferred root for collections or single objects. Inner namespace roots override outer ones, and a route option takes precedence over its namespace:
+
+```ruby
+namespace :users, root: 'members' do
+  get '/' do
+    User.all
+  end
+
+  get '/recent', root: 'recent_members' do
+    User.all
+  end
+end
+```
+
+Pass `root` to `render` to override namespace and route options for that response, including empty collections:
+
+```ruby
+get '/people', root: 'people' do
+  render User.all, adapter: :json, each_serializer: UserSerializer, root: 'members'
+end
+```
+
+This returns an object such as `{ "members": [{ "first_name": "Jane", "last_name": "Doe" }] }`; an empty collection returns `{ "members": [] }`.
+
+In AMS 0.10, `root: false` does not remove the `:json` adapter's envelope. To return a bare array for one response, choose the `:attributes` adapter:
+
+```ruby
+get '/people' do
+  render User.all, adapter: :attributes, each_serializer: UserSerializer
 end
 ```
 
+Return the model collection rather than a manually constructed `ActiveModel::Serializer::CollectionSerializer`. The formatter constructs the serializer and adapter; options such as `root` only affect the final response when the adapter handles them.
+
+### Single-Object Roots
+
+Starting in 3.0, explicit namespace roots apply to single-object responses as well as collections, with the same precedence: `render` overrides the route, the route overrides the innermost explicit namespace root, and inner namespace roots override outer ones.
+
+```ruby
+namespace :users, root: 'members' do
+  get '/:id' do
+    User.find(params[:id])
+  end
+end
+```
+
+With the `:json` adapter, this returns `{ "members": { "first_name": "Jane", "last_name": "Doe" } }`. The root is used literally, without singularizing it for a single object. In 2.x the namespace root was ignored for this response, which used `"user"` instead. See [UPGRADING](UPGRADING.md#upgrading-to-v300) for migration options.
+
+Without an explicit root, AMS continues to infer the single-object root from the serializer or model, not the namespace or route name. Adapter behavior is unchanged: `:attributes` returns an unwrapped object and `:json_api` retains its standard document structure.
+
 ### API Versioning
 
 If your Grape API is versioned you must namespace your serializers accordingly.
diff --git a/UPGRADING.md b/UPGRADING.md
index c1469c1..b54d315 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -1,3 +1,34 @@
+### Upgrading to v3.0.0
+
+#### Explicit namespace roots apply to single objects
+
+With the AMS `:json` adapter, an explicit namespace `root` now applies consistently to both collections and single objects. This intentionally changes single-object response keys that previously ignored the namespace root:
+
+```ruby
+namespace :users, root: 'members' do
+  get('/')    { User.all }
+  get('/:id') { User.find(params[:id]) }
+end
+```
+
+The collection uses `{ "members": [...] }`. In 3.0 the single-object response also uses `"members"`, returning `{ "members": {...} }` rather than the previous `{ "user": {...} }`. Roots are literal: a single-object response does not automatically singularize `"members"`.
+
+To preserve an existing single-object response key, override the namespace root on that route:
+
+```ruby
+namespace :users, root: 'members' do
+  get '/:id', root: 'user' do
+    User.find(params[:id])
+  end
+end
+```
+
+Alternatively, pass `root: 'user'` to `render` or remove the namespace root and specify collection roots on individual collection routes. Update API clients and response schemas if adopting the new namespace-derived key instead.
+
+Root precedence is `render` > route > innermost explicit namespace root > outer namespace roots > default serializer options. Without an explicit root, single objects retain AMS model/serializer inference; collections retain the innermost namespace or route-name default.
+
+The change is limited to explicit namespace roots. It does not change serializer inference, merge other namespace options differently, or alter adapter semantics. The `:attributes` adapter still omits envelopes, the `:json_api` adapter keeps its standard document structure, and `root: false` still does not remove a `:json` envelope.
+
 ### Upgrading to v1.5.0
 
 #### ASM v0.10.x support added, v0.9.x support dropped
diff --git a/lib/grape-active_model_serializers/endpoint_extension.rb b/lib/grape-active_model_serializers/endpoint_extension.rb
index a9abce1..b3303c6 100644
--- a/lib/grape-active_model_serializers/endpoint_extension.rb
+++ b/lib/grape-active_model_serializers/endpoint_extension.rb
@@ -44,7 +44,7 @@ def render(resources, extra_options = {})
         :meta, :meta_key
       )
       env['ams_adapter'] = options.slice(
-        :adapter, :serializer, :each_serializer, :include,
+        :adapter, :serializer, :each_serializer, :include, :root,
         :fields, :key_transform, :links, :namespace
       )
       env['ams_extra'] = options[:extra]
diff --git a/lib/grape-active_model_serializers/options_builder.rb b/lib/grape-active_model_serializers/options_builder.rb
index ea8fcff..7e3c88c 100644
--- a/lib/grape-active_model_serializers/options_builder.rb
+++ b/lib/grape-active_model_serializers/options_builder.rb
@@ -26,6 +26,7 @@ def endpoint_options
         [
           endpoint.default_serializer_options || {},
           endpoint.namespace_options,
+          namespace_root_options,
           endpoint.route_options,
           endpoint_metadata,
           endpoint.options,
@@ -33,6 +34,13 @@ def endpoint_options
         ].reduce(:merge)
       end
 
+      def namespace_root_options
+        scopes = endpoint.inheritable_setting.namespace_stackable[:namespace] || []
+        scopes.each_with_object({}) do |scope, options|
+          options.merge!(scope.options.slice(:root))
+        end
+      end
+
       def endpoint_metadata
         options = {}
         options[:for] = endpoint.api if endpoint.respond_to?(:api)
diff --git a/lib/grape-active_model_serializers/version.rb b/lib/grape-active_model_serializers/version.rb
index 97956cf..97e3c4a 100644
--- a/lib/grape-active_model_serializers/version.rb
+++ b/lib/grape-active_model_serializers/version.rb
@@ -1,5 +1,5 @@
 module Grape
   module ActiveModelSerializers
-    VERSION = '2.0.2'.freeze
+    VERSION = '3.0.0'.freeze
   end
 end
diff --git a/spec/features/grape-active_model_serializers/render_spec.rb b/spec/features/grape-active_model_serializers/render_spec.rb
index c2293c8..b7d2e04 100644
--- a/spec/features/grape-active_model_serializers/render_spec.rb
+++ b/spec/features/grape-active_model_serializers/render_spec.rb
@@ -115,3 +115,160 @@ def get_resource_with(meta)
     end
   end
 end
+
+describe 'single-object and collection roots' do
+  let(:app) { Class.new(Grape::API) }
+  let(:resources) { [User.new(first_name: 'Jane', last_name: 'Doe')] }
+  let(:outer_namespace_options) { { root: 'directory_members' } }
+  let(:inner_namespace_options) { { root: 'members' } }
+  let(:route_options) { {} }
+  let(:render_options) { {} }
+
+  before do
+    ActiveModelSerializers.config.adapter = :json
+    app.format :json
+    app.formatter :json, Grape::Formatter::ActiveModelSerializers
+
+    resource = resources
+    options = render_options
+    route_settings = route_options
+    outer_options = outer_namespace_options
+    inner_options = inner_namespace_options
+    app.namespace :directory, **outer_options do
+      namespace :users, **inner_options do
+        get '/people', **route_settings do
+          render resource, options
+        end
+      end
+    end
+
+    get '/directory/users/people'
+  end
+
+  it 'uses the innermost namespace root' do
+    expect(JSON.parse(last_response.body)).to eq(
+      'members' => [{ 'first_name' => 'Jane', 'last_name' => 'Doe' }]
+    )
+  end
+
+  context 'route options' do
+    let(:route_options) { { root: 'recent_members' } }
+
+    it 'overrides the namespace root' do
+      expect(JSON.parse(last_response.body)).to eq(
+        'recent_members' => [{ 'first_name' => 'Jane', 'last_name' => 'Doe' }]
+      )
+    end
+  end
+
+  context 'render options' do
+    let(:route_options) { { root: 'recent_members' } }
+    let(:render_options) { { root: 'selected_members' } }
+
+    it 'overrides the route and namespace roots' do
+      expect(JSON.parse(last_response.body)).to eq(
+        'selected_members' => [{ 'first_name' => 'Jane', 'last_name' => 'Doe' }]
+      )
+    end
+
+    context 'an empty collection' do
+      let(:resources) { [] }
+
+      it 'keeps the explicit root' do
+        expect(JSON.parse(last_response.body)).to eq('selected_members' => [])
+      end
+    end
+  end
+
+  context 'root is false' do
+    let(:render_options) { { root: false } }
+
+    it 'uses the AMS-inferred root rather than removing the JSON envelope' do
+      expect(JSON.parse(last_response.body)).to eq(
+        'users' => [{ 'first_name' => 'Jane', 'last_name' => 'Doe' }]
+      )
+    end
+  end
+
+  context 'the attributes adapter' do
+    let(:render_options) { { adapter: :attributes, root: 'ignored' } }
+
+    it 'returns a bare array regardless of the root option' do
+      expect(JSON.parse(last_response.body)).to eq(
+        [{ 'first_name' => 'Jane', 'last_name' => 'Doe' }]
+      )
+    end
+  end
+
+  context 'a single object' do
+    let(:resources) { User.new(first_name: 'Jane', last_name: 'Doe') }
+
+    it 'uses the same explicit namespace root as collections' do
+      expect(JSON.parse(last_response.body)).to eq(
+        'members' => { 'first_name' => 'Jane', 'last_name' => 'Doe' }
+      )
+    end
+
+    context 'an inner namespace without a root' do
+      let(:inner_namespace_options) { {} }
+
+      it 'inherits the outer namespace root' do
+        expect(JSON.parse(last_response.body)).to eq(
+          'directory_members' => { 'first_name' => 'Jane', 'last_name' => 'Doe' }
+        )
+      end
+    end
+
+    context 'no explicit namespace roots' do
+      let(:outer_namespace_options) { {} }
+      let(:inner_namespace_options) { {} }
+
+      it 'keeps the inferred model root' do
+        expect(JSON.parse(last_response.body)).to eq(
+          'user' => { 'first_name' => 'Jane', 'last_name' => 'Doe' }
+        )
+      end
+    end
+
+    context 'an inner namespace root is false' do
+      let(:inner_namespace_options) { { root: false } }
+
+      it 'uses the AMS-inferred root instead of inheriting the outer root' do
+        expect(JSON.parse(last_response.body)).to eq(
+          'user' => { 'first_name' => 'Jane', 'last_name' => 'Doe' }
+        )
+      end
+    end
+
+    context 'the attributes adapter' do
+      let(:render_options) { { adapter: :attributes } }
+
+      it 'keeps the response unwrapped despite the namespace root' do
+        expect(JSON.parse(last_response.body)).to eq(
+          'first_name' => 'Jane', 'last_name' => 'Doe'
+        )
+      end
+    end
+
+    context 'route options' do
+      let(:route_options) { { root: 'person' } }
+
+      it 'honors an explicit route root' do
+        expect(JSON.parse(last_response.body)).to eq(
+          'person' => { 'first_name' => 'Jane', 'last_name' => 'Doe' }
+        )
+      end
+    end
+
+    context 'render options' do
+      let(:route_options) { { root: 'person' } }
+      let(:render_options) { { root: 'selected_person' } }
+
+      it 'overrides the route root' do
+        expect(JSON.parse(last_response.body)).to eq(
+          'selected_person' => { 'first_name' => 'Jane', 'last_name' => 'Doe' }
+        )
+      end
+    end
+  end
+end