diff --git a/xml/System.Reflection/NullabilityInfoContext.xml b/xml/System.Reflection/NullabilityInfoContext.xml
index 2abcb3f555a..03d05b526bd 100644
--- a/xml/System.Reflection/NullabilityInfoContext.xml
+++ b/xml/System.Reflection/NullabilityInfoContext.xml
@@ -26,6 +26,7 @@
   <Docs>
     <summary>Provides APIs for populating nullability information and context from reflection members: <see cref="T:System.Reflection.ParameterInfo" />, <see cref="T:System.Reflection.FieldInfo" />, <see cref="T:System.Reflection.PropertyInfo" />, and <see cref="T:System.Reflection.EventInfo" />.</summary>
     <remarks>To be added.</remarks>
+    <threadsafe>This type is not thread safe. The <see cref="Overload:System.Reflection.NullabilityInfoContext.Create" /> methods can't be called concurrently from multiple threads, as they use a non-concurrent cache internally. Concurrent calls can result in an <see cref="T:System.InvalidOperationException" />. If you need to use <see cref="T:System.Reflection.NullabilityInfoContext" /> from multiple threads, use external synchronization.</threadsafe>
   </Docs>
   <Members>
     <Member MemberName=".ctor">
@@ -76,6 +77,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.EventInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="eventInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -107,6 +109,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.FieldInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="fieldInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -138,6 +141,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.ParameterInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="parameterInfo" /> is <see langword="null" />.</exception>
       </Docs>
@@ -169,6 +173,7 @@
         <summary>Populates a <see cref="T:System.Reflection.NullabilityInfo" /> for the given <see cref="T:System.Reflection.PropertyInfo" />. If the <c>nullablePublicOnly</c> feature is set for an assembly, like it does in the .NET SDK, the private and/or internal member's nullability attributes are omitted, and the API will return the <see cref="F:System.Reflection.NullabilityState.Unknown" /> state.</summary>
         <returns>A <see cref="T:System.Reflection.NullabilityInfo" /> instance.</returns>
         <remarks>To be added.</remarks>
+        <threadsafe>This method is not thread safe.</threadsafe>
         <exception cref="T:System.ArgumentNullException">
           <paramref name="propertyInfo" /> is <see langword="null" />.</exception>
       </Docs>