A Process Contribution is a special Process that externally defines additions and changes to an existing Process without directly modifying the existing Process. It achieves this by describing these additions and changes in a separate Process structure. This structures' elements relate to the other Process's elements using "Contributes" and "Replace" specializations. Process Contributions are normally packaged with Method Plug-ins that extend existing Method Plug-in with new capabilities.

A Process Contribution is a kind of "process plug-in" that plugs additional breakdown structures into an existing Process and therefore updates it afterwards with new or changed capabilities. For example, the J2EE Plug-in plugs into the technology independent main Plug-in. It may update the generic Delivery Processes defined in that Plug-in with J2EE specific Activities. A respective ".NET Plug-in" could define similar updates relevant for that technology platform. A process practitioner could then apply the chosen Plug-in, thereby generating a technology specific Process, but keeping maintenance of his/her Processes minimal, because technology specific parts are kept separate and will be applied on demand only.