The report represents the results of a broad investigation that seeks to advance the state-of-the art of the data analysis techniques used to predict system reliability and maintainability. Principally, this study was directed toward development of a reliability prediction-by-function technique for avionic equipment and units. As a result of the large scale data collection and analysis program carried out during this study, a series of equations have been formulated which permits the prediction of mean-time-between-failures through a knowledge of selected performance parameters; these parameters represent quantities that are generally known early in the design cycle, enabling reliability predictions by function to be made long before parts population and stress data, the basis of existing prediction techniques, become available. Also, as a result of this study, the development of maintainability prediction-by-function techniques for avionic equipment was determined to be feasible. Predictions in terms of shop-mean-time-to-repair, based on general design characteristics, were shown to be achievable. The feasibility of drawing useful reliability design guidelines from engineering and data analysis also was established. It was determined that design criteria can be formulated to benefit the circuit designers. (Author).