The Franciscan Report

Suzanne Cook's .NET CLR Notes : New Assembly, Old .NET (and Vice-Versa)

To load the assembly compiled using the previous version of .Net framework such as 1.1, or lower, from a .Net 2.0, you don't have to do any extra effort.

However, things are not the same the other way around, to be able to load a .Net 2.0 assembly from a previous version of .Net you have to add this into your App.config

 
<startup> 
    <supportedRuntime version="v2.0.50727" /> 
    <supportedRuntime version="v2.0.50215" /> 
    <supportedRuntime version="v2.0.40607" /> 
    <supportedRuntime version="v1.1.4322" /> 
    <supportedRuntime version="v1.0.3705" /> 
    <requiredRuntime version="v1.0.3705" /> 
</startup> 

This will allows such case, assuming you have the required version of .Net and the supported runtime version of .net 2.0