Agent-oriented Conceptual Modelling (AoCM, as exemplified by the i* notation [Modelling Strategic Relationships for Process Reengineering], represents an interesting approach to modelling early phase requirements that is particularly effective in capturing organizational contexts, stake-holder intentions and rationale. There are significant benefits in using formal methods for the development of computer systems and improving their quality. We propose a methodology which permits the use of these two otherwise disparate approaches in a complementary and synergistic fashion for requirements engineering.