diff --git a/src/UglyToad.PdfPig.Tests/Integration/Documents/Layer pdf - 322_High_Holborn_building_Brochure.pdf b/src/UglyToad.PdfPig.Tests/Integration/Documents/Layer pdf - 322_High_Holborn_building_Brochure.pdf
new file mode 100644
index 00000000..5363c286
Binary files /dev/null and b/src/UglyToad.PdfPig.Tests/Integration/Documents/Layer pdf - 322_High_Holborn_building_Brochure.pdf differ
diff --git a/src/UglyToad.PdfPig.Tests/Integration/OptionalContentTests.cs b/src/UglyToad.PdfPig.Tests/Integration/OptionalContentTests.cs
index 78719aa3..de7dcbf4 100644
--- a/src/UglyToad.PdfPig.Tests/Integration/OptionalContentTests.cs
+++ b/src/UglyToad.PdfPig.Tests/Integration/OptionalContentTests.cs
@@ -1,4 +1,6 @@
-using Xunit;
+using System;
+using UglyToad.PdfPig.Tokens;
+using Xunit;
 
 namespace UglyToad.PdfPig.Tests.Integration
 {
@@ -10,7 +12,7 @@ namespace UglyToad.PdfPig.Tests.Integration
             using (var document = PdfDocument.Open(IntegrationHelpers.GetDocumentPath("odwriteex.pdf")))
             {
                 var page = document.GetPage(1);
-                var oc = page.GetOptionalContents();
+                var oc = page.ExperimentalAccess.GetOptionalContents();
 
                 Assert.Equal(3, oc.Count);
 
@@ -23,5 +25,30 @@ namespace UglyToad.PdfPig.Tests.Integration
                 Assert.Equal(1, oc["Text"].Count);
             }
         }
+
+        [Fact]
+        public void MarkedOptionalContentRecursion()
+        {
+            using (var document = PdfDocument.Open(IntegrationHelpers.GetDocumentPath("Layer pdf - 322_High_Holborn_building_Brochure.pdf")))
+            {
+                var page1 = document.GetPage(1);
+                var oc1 = page1.ExperimentalAccess.GetOptionalContents();
+                Assert.Equal(16, oc1.Count);
+                Assert.Contains("NEW ARRANGEMENT", oc1);
+
+                var page2 = document.GetPage(2);
+                var oc2 = page2.ExperimentalAccess.GetOptionalContents();
+                Assert.Equal(15, oc2.Count);
+                Assert.DoesNotContain("NEW ARRANGEMENT", oc2);
+                Assert.Contains("WDL Shell text", oc2);
+                Assert.Equal(2, oc2["WDL Shell text"].Count);
+
+                var page3 = document.GetPage(3);
+                var oc3 = page3.ExperimentalAccess.GetOptionalContents();
+                Assert.Equal(15, oc3.Count);
+                Assert.Contains("WDL Shell text", oc3);
+                Assert.Equal(2, oc3["WDL Shell text"].Count);
+            }
+        }
     }
 }
diff --git a/src/UglyToad.PdfPig/Content/OptionalContentGroupElement.cs b/src/UglyToad.PdfPig/Content/OptionalContentGroupElement.cs
index 587b7d22..2732bcbd 100644
--- a/src/UglyToad.PdfPig/Content/OptionalContentGroupElement.cs
+++ b/src/UglyToad.PdfPig/Content/OptionalContentGroupElement.cs
@@ -30,7 +30,7 @@ namespace UglyToad.PdfPig.Content
         /// <summary>
         /// A usage dictionary describing the nature of the content controlled by the group.
         /// </summary>
-        public IDictionary<string, object> Usage { get; }
+        public IReadOnlyDictionary<string, IToken> Usage { get; }
 
         /// <summary>
         /// Underlying <see cref="MarkedContentElement"/>.
@@ -110,7 +110,7 @@ namespace UglyToad.PdfPig.Content
                     // Usage - Optional
                     if (markedContentElement.Properties.TryGet(NameToken.Usage, out DictionaryToken usage))
                     {
-                        throw new NotImplementedException();
+                        this.Usage = usage.Data;
                     }
                     break;
 
@@ -119,29 +119,29 @@ namespace UglyToad.PdfPig.Content
                     if (markedContentElement.Properties.TryGet(NameToken.Ocgs, out DictionaryToken ocgsD))
                     {
                         // dictionary or array
-                        throw new NotImplementedException();
+                        throw new NotImplementedException($"{NameToken.Ocgs}");
                     }
                     else if (markedContentElement.Properties.TryGet(NameToken.Ocgs, out ArrayToken ocgsA))
                     {
                         // dictionary or array
-                        throw new NotImplementedException();
+                        throw new NotImplementedException($"{NameToken.Ocgs}");
                     }
 
                     // P - Optional
                     if (markedContentElement.Properties.TryGet(NameToken.P, out NameToken p))
                     {
-                        throw new NotImplementedException();
+                        throw new NotImplementedException($"{NameToken.P}");
                     }
 
                     // VE - Optional
                     if (markedContentElement.Properties.TryGet(NameToken.VE, out ArrayToken ve))
                     {
-                        throw new NotImplementedException();
+                        throw new NotImplementedException($"{NameToken.VE}");
                     }
                     break;
 
                 default:
-                    throw new ArgumentException($"Unknown Optional Content of type '{Type}'.", nameof(Type));
+                    throw new ArgumentException($"Unknown Optional Content of type '{Type}' not known.", nameof(Type));
             }
         }
 
diff --git a/src/UglyToad.PdfPig/Content/Page.cs b/src/UglyToad.PdfPig/Content/Page.cs
index f27bae0d..9ce53278 100644
--- a/src/UglyToad.PdfPig/Content/Page.cs
+++ b/src/UglyToad.PdfPig/Content/Page.cs
@@ -10,6 +10,7 @@
     using Util.JetBrains.Annotations;
     using Tokenization.Scanner;
     using Graphics;
+    using System.Linq;
 
     /// <summary>
     /// Contains the content and provides access to methods of a single page in the <see cref="PdfDocument"/>.
@@ -166,11 +167,6 @@
         /// </summary>
         public IReadOnlyList<MarkedContentElement> GetMarkedContents() => Content.GetMarkedContents();
 
-        /// <summary>
-        /// Gets any optional content on the page.
-        /// </summary>
-        public IDictionary<string, IReadOnlyList<OptionalContentGroupElement>> GetOptionalContents() => Content.GetOptionalContents();
-
         /// <summary>
         /// Provides access to useful members which will change in future releases.
         /// </summary>
@@ -198,6 +194,42 @@
             {
                 return annotationProvider.GetAnnotations();
             }
+
+            /// <summary>
+            /// Gets any optional content on the page.
+            /// <para>Does not handle XObjects and annotations for the time being.</para>
+            /// </summary>
+            public IDictionary<string, IReadOnlyList<OptionalContentGroupElement>> GetOptionalContents()
+            {
+                // 4.10.2
+                // Optional content in content stream
+                var mc = page.Content?.GetMarkedContents();
+
+                List<OptionalContentGroupElement> mcesOptional = new List<OptionalContentGroupElement>();
+                GetOptionalContentsRecursively(mc, ref mcesOptional);
+
+                // Optional content in XObjects and annotations
+                // TO DO
+                //var annots = GetAnnotations().ToList();
+
+                return mcesOptional.GroupBy(oc => oc.Name).ToDictionary(g => g.Key, g => g.ToList() as IReadOnlyList<OptionalContentGroupElement>);
+            }
+
+            private void GetOptionalContentsRecursively(IReadOnlyList<MarkedContentElement> markedContentElements, ref List<OptionalContentGroupElement> mcesOptional)
+            {
+                foreach (var mce in markedContentElements)
+                {
+                    if (mce.Tag == "OC")
+                    {
+                        mcesOptional.Add(new OptionalContentGroupElement(mce));
+                        // we don't recurse
+                    }
+                    else if (mce.Children?.Count > 0)
+                    {
+                        GetOptionalContentsRecursively(mce.Children, ref mcesOptional);
+                    }
+                }
+            }
         }
     }
 }
diff --git a/src/UglyToad.PdfPig/Content/PageContent.cs b/src/UglyToad.PdfPig/Content/PageContent.cs
index 065a764c..0e645df3 100644
--- a/src/UglyToad.PdfPig/Content/PageContent.cs
+++ b/src/UglyToad.PdfPig/Content/PageContent.cs
@@ -67,24 +67,5 @@
         }
 
         public IReadOnlyList<MarkedContentElement> GetMarkedContents() => markedContents;
-
-        public IDictionary<string, IReadOnlyList<OptionalContentGroupElement>> GetOptionalContents()
-        {
-            const string ocTag = "OC";
-
-            List<OptionalContentGroupElement> optionalContent = new List<OptionalContentGroupElement>();
-
-            // 4.10.2
-            // Optional content in content stream
-            foreach (var omc in GetMarkedContents().Where(mc => mc.Tag == ocTag))
-            {
-                optionalContent.Add(new OptionalContentGroupElement(omc));
-            }
-
-            // Optional content in XObjects and annotations
-            // TO DO
-
-            return optionalContent.GroupBy(oc => oc.Name).ToDictionary(g => g.Key, g => g.ToList() as IReadOnlyList<OptionalContentGroupElement>);
-        }
     }
 }