32-bit versus 64-bit ODP.NET to Oracle connection I seem to be having an issue connecting a 32-bit .NET application to a 64-bit server, without a full Oracle client.

If I build a 64-bit application, using the 64-bit ODP.NET dll's or a 64-bit instant client, everything seems to work fine. But if I build a 32-bit ODP.NET application or use the 32-bit instant client, it always goes "looking" for the 64-bit dll's, and errors out on me.

Has anyone encountered this before, or have any suggestions as to what issues we might be having?

We don't have the same problem connecting to SQL Server (of course, SQL server uses mixed-mode assemblies...)
Did you control PATH Environment Variable to which comes first, 32 or 64. Which ever client is installed last,  change PATH accordingly. I have encountered similar issue. Windows uses PATH environment variable to decide which dlls to load. I have two clients installed in my machine and used PATH variable to force which one to use.

C:\oracle\product\11.2.0&gt;dir
 Directory of C:\oracle\product\11.2.0

20.09.2011  10:07    &lt;DIR&gt;          .
20.09.2011  10:07    &lt;DIR&gt;          ..
20.09.2011  10:08    &lt;DIR&gt;          client32Bit
20.09.2011  10:04    &lt;DIR&gt;          client64Bit

C:\oracle\product\11.2.0&gt;echo %PATH%

XXXX;C:\oracle\product\11.2.0\client64Bit\BIN;