Based mainly on interviews conducted at 14 federal agencies that had completed or were involved in software conversion projects, this publication provides guidelines for the entire process of software conversion. This is defined as the transformation, without functional change, of computer programs or data elements to permit their use on a replacement or changed data processing or teleprocessing system or service. It is noted that a conversion involving non-code compatible machines is assumed since this situation produces the most problems. Following introductory information, six phases of the conversion life cycle are described: project initiation; the conversion requirements phase where studies and analyses are conducted to identify agency requirements and cost considerations; the conversion planning phase; the conversion preparation phase; the actual conversion phase; and the post-conversion phase. The objectives, activities, and management considerations involved in each phase are outlined. Appendices include a 51-item bibliography; a list of 23 conversion directives, standards, and other references produced by the federal government; an extensive methodology for software conversion costing; 11 case studies of software conversion projects at federal agencies; and a 27-item glossary. (ESR)