This paper describes a computer-supported environment designed to facilitate distance learning through collaborative problem-solving. The goal is to encourage distance learning students to work together, in order to promote both learning of collaboration and learning through collaboration. Collaboration is defined as working together on a common problem, communicating, and coordinating activities towards a shared goal. A system is proposed embedding three models: an activity model, a domain model, and a conversational model. The system can support asynchronous collaboration in a number of dimensions: giving structure to activities and communication to articulate the problem-solving task; supplying a share space to build jointly common knowledge; providing relevant know-how by case and techniques libraries; and facilitating further reflection on the whole learning process. Preliminary results indicate that this approach is promising regarding establishing collaborative distance frameworks to enhance students' learning processes. Topics discussed include: features of the distance learning scenario, including institutional framework, kind of scenario, learners, settings, and facilities; the modeling approach used; and developing an application, including the activity model, dialogue model, domain model, and learner interface. A table presents the definition of specification as a complex activity; and a figure illustrates the learner interface. (Author/DLS)