Web-based learning programs enable learners to browse web pages individually through a predefined path or a personalized routine. However, they provide less social context and cooperative context for cooperation. The main idea presented in this poster is the concept of "informal cooperative learning program". It is defined as a set of structured learning steps. Learners can go through all steps by following the structure at different paces, but they are supported to perform cooperative learning when they happen to be at the same step. This idea has been implemented in our prototype system COMPILE (Cooperative Open Multimedia-based Process-centered Integrated Learning Environment).