diff --git a/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableCollectionThreadSafe.cs b/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableCollectionThreadSafe.cs
index ae0bf80..442bfa3 100644
--- a/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableCollectionThreadSafe.cs
+++ b/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableCollectionThreadSafe.cs
@@ -96,6 +96,25 @@ public void Move(int oldIndex, int newIndex)
             }
         }
 
+        public void Reset()
+        {
+            var notifyAndWait = WaitOnNotifying;
+
+            if (notifyAndWait)
+                _ReaderWriterLockSlim.EnterUpgradeableReadLock();
+            try
+            {
+                OnPropertyChanged(nameof(Count));
+                OnPropertyChanged(_IndexerName);
+                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+            }
+            finally
+            {
+                if (notifyAndWait)
+                    _ReaderWriterLockSlim.ExitUpgradeableReadLock();
+            }
+        }
+
         public new void Add(T item)
         {
             var notifyAndWait = WaitOnNotifying;
diff --git a/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableDictionaryThreadSafe.cs b/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableDictionaryThreadSafe.cs
index 12a2375..e27c79c 100644
--- a/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableDictionaryThreadSafe.cs
+++ b/src/ThunderDesign.Net-PCL.Threading/Collections/ObservableDictionaryThreadSafe.cs
@@ -169,6 +169,26 @@ public bool WaitOnNotifying
             return result;
         }
 
+        public void Reset()
+        {
+            var notifyAndWait = WaitOnNotifying;
+
+            if (notifyAndWait)
+                _ReaderWriterLockSlim.EnterUpgradeableReadLock();
+            try
+            {
+                OnPropertyChanged(nameof(Keys));
+                OnPropertyChanged(nameof(Values));
+                OnPropertyChanged(nameof(Count));
+                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+            }
+            finally
+            {
+                if (notifyAndWait)
+                    _ReaderWriterLockSlim.ExitUpgradeableReadLock();
+            }
+        }
+
 #if NET6_0_OR_GREATER
         public new bool TryAdd(TKey key, TValue value)
         {
diff --git a/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableCollectionThreadSafe.cs b/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableCollectionThreadSafe.cs
index 6540cd3..d730078 100644
--- a/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableCollectionThreadSafe.cs
+++ b/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableCollectionThreadSafe.cs
@@ -9,6 +9,7 @@ public interface IObservableCollectionThreadSafe : ICollectionThreadSafe, IBinda
     {
         #region methods
         void Move(int oldIndex, int newIndex);
+        void Reset();
         #endregion
     }
 
diff --git a/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableDictionaryThreadSafe.cs b/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableDictionaryThreadSafe.cs
index 27891d8..ee1d7a7 100644
--- a/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableDictionaryThreadSafe.cs
+++ b/src/ThunderDesign.Net-PCL.Threading/Interfaces/IObservableDictionaryThreadSafe.cs
@@ -5,6 +5,7 @@ namespace ThunderDesign.Net.Threading.Interfaces
 {
     public interface IObservableDictionaryThreadSafe : IDictionaryThreadSafe, IBindableCollection
     {
+        void Reset();
     }
 
     public interface IObservableDictionaryThreadSafe<TKey, TValue> : IDictionaryThreadSafe<TKey, TValue>, IObservableDictionaryThreadSafe