diff --git a/AgileMapper.UnitTests/Configuration/WhenConfiguringDataSources.cs b/AgileMapper.UnitTests/Configuration/WhenConfiguringDataSources.cs
index 259438a8c..b7bc09b5d 100644
--- a/AgileMapper.UnitTests/Configuration/WhenConfiguringDataSources.cs
+++ b/AgileMapper.UnitTests/Configuration/WhenConfiguringDataSources.cs
@@ -1161,6 +1161,29 @@ public void ShouldAllowIdAndIdentifierConfiguration()
             }
         }
 
+        // See https://github.com/agileobjects/AgileMapper/issues/146
+        [Fact]
+        public void ShouldApplyAConfiguredSourceInterfaceMember()
+        {
+            using (var mapper = Mapper.CreateNew())
+            {
+                mapper.WhenMapping
+                    .From<Issue146.Source.Container>().To<Issue146.Target.Cont>()
+                    .Map(ctx => ctx.Source.Empty).To(tgt => tgt.Info);
+
+                var source = new Issue146.Source.Container("12321") { Name = "input" };
+                var result = mapper.Map(source).ToANew<Issue146.Target.Cont>();
+
+                result.ShouldNotBeNull();
+                result.Name.ShouldBe("input");
+                result.Info.ShouldNotBeNull();
+                result.Info.Id.ShouldBe("12321");
+                
+                // Source has a .Value member, but we don't runtime-type interfaces
+                result.Info.Value.ShouldBeNull();
+            }
+        }
+
         // See https://github.com/agileobjects/AgileMapper/issues/64
         [Fact]
         public void ShouldApplyAConfiguredRootSource()
@@ -1794,5 +1817,54 @@ public class DataTarget
                 public OtherDataTarget oth;
             }
         }
+
+        internal static class Issue146
+        {
+            public static class Source
+            {
+                public interface IData
+                {
+                    string Id { get; set; }
+                }
+
+                public interface IEmpty : IData { }
+
+                public class Data : IEmpty
+                {
+                    public string Id { get; set; }
+
+                    public string Value => "Data.Value!";
+                }
+
+                public class Container
+                {
+                    public Container(string infoId)
+                    {
+                        Empty = new Data { Id = infoId };
+                    }
+
+                    public string Name { get; set; }
+
+                    public IEmpty Empty { get; }
+                }
+            }
+
+            public static class Target
+            {
+                public class Data
+                {
+                    public string Id { get; set; }
+
+                    public string Value { get; set; }
+                }
+
+                public class Cont
+                {
+                    public Data Info { get; set; }
+
+                    public string Name { get; set; }
+                }
+            }
+        }
     }
 }
diff --git a/AgileMapper.UnitTests/WhenViewingMappingPlans.cs b/AgileMapper.UnitTests/WhenViewingMappingPlans.cs
index 802d8a5fc..38a754202 100644
--- a/AgileMapper.UnitTests/WhenViewingMappingPlans.cs
+++ b/AgileMapper.UnitTests/WhenViewingMappingPlans.cs
@@ -327,6 +327,17 @@ public void ShouldNotAttemptUnnecessaryObjectCreationCallbacks()
             }
         }
 
+        // See https://github.com/agileobjects/AgileMapper/issues/146
+        [Fact]
+        public void ShouldUseBaseInterfaceTypeSourceMembersWithoutRuntimeTyping()
+        {
+            string plan = Mapper
+                .GetPlanFor<Issue146.Source.Container>()
+                .ToANew<Issue146.Target.Cont>();
+
+            plan.ShouldContain("data.Id = cToCData.Source.Info.Id;");
+        }
+
         [Fact]
         public void ShouldShowEnumMismatches()
         {
@@ -408,5 +419,56 @@ public void ShouldShowAllCachedMappingPlans()
                 mapper.RootMapperCountShouldBe(5);
             }
         }
+
+        #region Helper Classes
+
+        internal static class Issue146
+        {
+            public static class Source
+            {
+                public interface IData
+                {
+                    string Id { get; set; }
+                }
+
+                public interface IEmpty : IData { }
+
+                public class Data : IEmpty
+                {
+                    public string Id { get; set; }
+                }
+
+                public class Container
+                {
+                    public Container(string infoId)
+                    {
+                        Info = new Data { Id = infoId };
+                    }
+
+                    public string Name { get; set; }
+
+                    public IEmpty Info { get; }
+                }
+            }
+
+            public static class Target
+            {
+                public class Data
+                {
+                    public string Id { get; set; }
+
+                    public string Value { get; set; }
+                }
+
+                public class Cont
+                {
+                    public Data Info { get; set; }
+
+                    public string Name { get; set; }
+                }
+            }
+        }
+
+        #endregion
     }
 }
diff --git a/AgileMapper/DataSources/Finders/DataSourceFindContext.cs b/AgileMapper/DataSources/Finders/DataSourceFindContext.cs
index e5d72f387..27c0a0a01 100644
--- a/AgileMapper/DataSources/Finders/DataSourceFindContext.cs
+++ b/AgileMapper/DataSources/Finders/DataSourceFindContext.cs
@@ -47,13 +47,11 @@ private IList<IConfiguredDataSource> GetConfiguredDataSources(IMemberMapperData
         public IDataSource GetFallbackDataSource()
             => ChildMappingData.RuleSet.FallbackDataSourceFactory.Create(MapperData);
 
-        public IDataSource GetFinalDataSource(IDataSource foundDataSource, IChildMemberMappingData mappingData = null)
+        public IDataSource GetFinalDataSource(IDataSource foundDataSource)
+            => GetFinalDataSource(foundDataSource, ChildMappingData);
+        
+        public IDataSource GetFinalDataSource(IDataSource foundDataSource, IChildMemberMappingData mappingData)
         {
-            if (mappingData == null)
-            {
-                mappingData = ChildMappingData;
-            }
-
             var childTargetMember = mappingData.MapperData.TargetMember;
 
             if (UseComplexTypeDataSource(foundDataSource, childTargetMember))
diff --git a/AgileMapper/Members/MemberCache.cs b/AgileMapper/Members/MemberCache.cs
index 980ce4ee1..c22bbe37d 100644
--- a/AgileMapper/Members/MemberCache.cs
+++ b/AgileMapper/Members/MemberCache.cs
@@ -1,6 +1,7 @@
 namespace AgileObjects.AgileMapper.Members
 {
     using System;
+    using System.Collections;
     using System.Collections.Generic;
     using System.Linq;
     using System.Reflection;
@@ -33,7 +34,31 @@ public IList<Member> GetSourceMembers(Type sourceType)
                 var properties = GetProperties(key.Type, OnlyGettable);
                 var methods = GetMethods(key.Type, OnlyRelevantCallable, Member.GetMethod);
 
-                return GetMembers(fields, properties, methods);
+                var members = new[] { fields, properties, methods };
+
+                if (!key.Type.IsInterface())
+                {
+                    return GetMembers(members);
+                }
+
+                var interfaceTypes = key.Type.GetAllInterfaces();
+
+                if (interfaceTypes.Length == 0)
+                {
+                    return GetMembers(members);
+                }
+
+                var interfaceCount = interfaceTypes.Length;
+                
+                var allMembers = new IEnumerable<Member>[3 + interfaceCount];
+                allMembers.CopyFrom(members);
+
+                for (var i = 0; i < interfaceCount; ++i)
+                {
+                    allMembers[i + 3] = GetSourceMembers(interfaceTypes[i]);
+                }
+                
+                return GetMembers(allMembers);
             });
         }
 
@@ -132,12 +157,6 @@ private static bool OnlyCallableSetters(MethodInfo method)
         #endregion
 
         private static IList<Member> GetMembers(params IEnumerable<Member>[] members)
-        {
-            var allMembers = members
-                .SelectMany(m => m)
-                .ToArray();
-
-            return allMembers;
-        }
+            => members.SelectMany(m => m).ToArray();
     }
 }