This is the guide to the computer program LOGIST for program users who want to obtain estimates for examinees' abilities and item characteristic curve parameters with the minimum of input required by the program. Input requirements, final output, intermediate printouts, the estimation procedure, requirements for convergence, program considerations and availability, and the method for determining initial estimates for ability and the item parameters, and the criteria for terminating the program, are all described. The only input required is the number of items, the number of examinees, the number of alternative choices per item and the coded responses of each examinee to each item. The final output contains the estimated item parameters and abilities, printed and punched. It may be necessary for convergence to have a reasonably large number of items, say 40 or more, and a reasonably large number of examinees, say 100 or more. The appendices describe the input, printed and punched output, and the program in IBM 360 JCL to put LOGIST in a user library and execute the test data.