The Opinionnaire on Political Institutions and Participation (OPIP) was designed to measure six dimensions of the overall construct of political attitude. Three studies were undertaken to determine the validity and reliability of the instrument, and the OPIP was found to be a valid and reliable instrument for research and evaluations using multi-subject designs. Validation and cross-validation studies indicated that the instrument was construct valid for measuring political attitudes. Reliability studies indicated that overall test-pretest and internal consistency were moderately high. Studies of the reliability of the six subtests indicated that test-retest and internal consistency ranged from moderate to low. (Author)