This report describes the accomplishments during a 3-year R&D program to design, develop, fabricate and evaluate two full scale engineering models of a Tactical Rubidium Frequency Standard (TRFS). The TRFS is a miniature atomic time and frequency source that is capable of operation in a harsh tactical military environment. In particular, it incorporates advances in miniaturization, ruggedness, fast warmup and high temperature operation that are required for aircraft applications. The report includes a detailed description of the TRFS design and the results of qualification tests on the two full scale engineering models. All program objectives were met. Keywords: Rubidium frequency standard.