Problem-solving methods (PSM) are abstract structures that describe specific reasoning processes employed to solve a set of similar problems. We envisage that off-the-shelf PSMs can assist in the development of agent-oriented solutions, not only as reusable and extensible components that software engineers employ for designing agent architecture solutions, but just as importantly as a set of runtime capabilities that agents themselves dynamically employ in order to solve problems. This chapter describes PSMs for agent-oriented software engineering (AOSE) that address interaction-dependent problem-solving such as negotiation or cooperation. An extension to an AOSE methodology MOBMAS is proposed whereby PSMs are integrated in the software development phases of MAS Organization Design, Internal Design, and Interaction Design. In this way, knowledge engineering drives the development of agent-oriented systems.