In June 1995, the Idaho Joint Legislative Oversight Committee directed the Office of Performance Evaluations to conduct an evaluation of school district pupil transportation. This report, the last in a series of four, examines the apparent cost difference between district-operated transportation programs and those that are contracted to transportation providers. The report also explains how the processes of reimbursing districts and calculating ratios used for comparative purposes affect the apparent cost difference. Data were gathered through analysis of state and district records, a survey of all 110 Idaho school districts with student-transportation programs, interviews, and visits to nine school districts. Analysis of department cost ratios suggests that contracting is more expensive than district-operated programs. However, the cost ratios do not accurately describe district efficiency. Because a detailed analysis on an individual district basis was beyond the scope of the requested evaluation, the report does not conclude that one means of providing services is more efficient than the other. The reasons for the apparent cost differences fall into four categories: different cost components, application of department rules and reimbursement practices, characteristics of district transportation programs, and calculation of district measurement ratios. Nine tables and five figures are included. A separate volume of appendices contains reimbursable cost ratios for Idaho school districts, a copy of the pupil-transportation survey, statutes and administrative rules governing pupil transportation, a sample Department of Education reimbursement claim form and instructions, and general methods for estimating effects on reimbursable cost ratios. (LMI)