The success of any software development project depends in part on the quality of the communication among the individuals involved: users, designers, coders and managers. On large systems, a variety of individuals perform various tasks at different points in time. The efficiency and correctness with which later tasks are performed depends critically on the documentation supplied during previous phases of the development cycle. This paper describes a series of three experiments designed to examine the effects of documentation format on the performance of programmers on different software-related tasks.