Process reuse (the ability to construct new processes by assembling already built ones) and process harvesting (the ability to build generic processes that may be further reused, from existing ones) are two crucial issues in process technology. Both of them involve the definition of a set of mechanisms, like abstraction, adaptation, composition, etc., which are appropriate to achieve their goals. In this article, we define a general framework to process reuse and harvesting that proposes a complete set of mechanisms to deal with both activities. This general framework is particularized to the context of the PROMENAE software process modelling language. A process reuse case study which composes various reuse mechanisms is presented in the context of PROMENADE.