Using data submitted by probation officers in nine pilot courts, validity tests were conducted on all the variables in the study, using a .01 level of statistical significance. Offender characteristics associated with probation failure were found to be male, under 19 years-old, committed a property crime, unemployed for 6 months or less during the past year, a substance abuse problem, and a general attitude problem. Clients characterized as needing maximum supervision had the highest probability of probation failure. Prior record, prior probation revocations, age at first conviction, time employed or in school, family structure, substance abuse, and attitude were found to be significantly associated with probation failure. Probation failures were also found to have greater needs in the areas of education, employment, marital and family problems, social relations, alcohol and drug use, counseling, living arrangements, and financial management. Only health needs did not appear greater among probation failures than among probation successes. Nearly 90 precent of new offenses were found to occur within the first 6 months of probation supervision, suggesting that immediate and intense probation intervention is essential to supporting lawabiding behavior by the probationer. Forms used in the assessment of client risk and needs/strengths are appended. For related material, see NCJ 82546 and 87064-65. (Author summary modified)