>Make sure the client threads are STA style threads. Otherwise you'll get all sorts of problems, although blocking should not be one of them.
>
>Are you createing new instances of your object on each thread? That would be the other requirement for this to work - the object must be called from the same thread that created it.

It works now.

It seems like the Delphi framework was caching Delphi objects, but not keeping them on the same thread.

I had not seen any documentation about staying on the same thread, so your advice definitely got me on the right track.

Thanks Rick!