This volume contains the background texts for an IFIP State-of-the-Art Seminar on Formal Program Development, held in early 1992 near Rio de Janeiro, Brazil. The book stems from work done by IFIP Working Group 2.1 on Algorithmic Languages and Calculi. Since 1975, the Working Group has increasingly focused on systematic approaches to programming and on appropriate concepts and notations to support such approaches. Today, the calculation of programs from specifications constitutes the central theme ofthe group's work. Thus the core interests of the group are: - formal specification of solutions to problems, and - formal development/calculationof programs from such specifications.