Critical to precise quantitative research is reliability estimation. Researchers have limited tools, however, to assess the reliability of evolving instruments. Consequently, cursory assessment is typical and in-depth evaluation is rare. This paper presents a rationale for and description of PIAS, a computerized instrument analysis system. PIAS makes two major contributions to measurement theory and practice: (1) PIAS is a collection of most of the routines necessary for such analyses in one user-oriented package, and (2) PIAS provides unique output allowing the user to identify the most efficient combination of items; i.e., the smallest number of items with the highest reliability. A utilization agreement and order form for PIAS is included. (Author/RC)