Modula-2 was designed in 1979 by Prof. Niklaus Wirth as a successor to Pascal. It provides similar facilities for the description of algorithms and data structures, but differs radically from Pascal in allowing the composition of programs from separately compiled modules in a carefully controlled way. This paper recounts some experiences with implementing the languages for a variety of computers, and describes a collection of tools (mostly written in Modula-2) that provides an extensive program development environment for the language. In particular, a general set of run time libraries is described together with utilities for consistent compilation, symbolic debugging and run time profiling. The paper concludes with some observations on the language formed on the basis of these experiences.