STUDY SUBJECTS INCLUDED A SAMPLE OF 3,291 ADULTS ARRESTED IN 1973 FOR DIVERTIBLE DRUG OFFENSES; 981 WERE DIVERTED TO TREATMENT AND EDUCATION PROGRAMS AND 2,310 WERE PROCESSED THROUGH THE COURTS. A SAMPLE OF 1,002 ADULTS ARRESTED IN 1972 FOR DRUG OFFENSES DEFINED IN 1973 AS DIVERTIBLE SERVED AS A COMPARISON (PREDIVERSION) GROUP. THE 1973 GROUP HAD A SIGNIFICANTLY HIGHER PROPORTION OF MARIJUANA OFFENDERS THAN THE 1972 GROUP, BUT THE GROUPS WERE STATISTCALLY COMPARABLE IN OTHER RESPECTS. THE 1973 DIVERTED SUBGROUP WAS MADE UP OF A DISPROPORTIONATE NUMBER OF SUBJECTS WHO WOULD BE RELATIVELY UNLIKELY TO RECIDIVATE UNDER ANY CIRCUMSTANCES (I.E., PERSONS WITH NO PRIOR ARRESTS WHO HAD BEEN ARRESTED FOR POSSESSION OF MARIJUANA). REARREST RATES 1 YEAR AFTER THE FIRST OFFENSE WERE 42 PERCENT FOR 1972 ARRESTEES, 31 PERCENT FOR ALL 1973 ARRESTES, 21 PERCENT FOR DIVERTED 1973 ARRESTEES, AND 35 PERCENT FOR NONDIVERTED 1973 ARRESTEES. CONVICTION RATES FOR 1972 AND 1973 REARRESTEES WERE COMPARABLE (38 AND 36 PERCENT, RESPECTIVELY). REARREST RATES WERE HIGHEST FOR MALES, MEXICAN-AMERICANS, BLACKS, SUBJECTS UNDER 20, SUBJECTS WITH PRIOR DRUG ARRESTS, AND SUBJECTS ARRESTED FOR NARCOTIC OR DANGEROUS DRUG OFFENSES. APROXIMATELY 54 PERCENT OF THE 1972 REARRESTEES WERE REARRESTED FOR DRUG OFFENSES, COMPARED TO 46 PERCENT FOR 1973 REARRESTEES (48 PERCENT FOR DIVERTED, 45 PERCENT FOR NONDIVERTED). THE UNANTICIPATED FINDING THAT RECIDIVISM WAS LOWER FOR 1973 NONDIVERTED SUBJECTS THAN FOR PREDIVERSION SUBJECTS SUGGESTS THAT FACTORS OTHER THAN THE DIVERSION PROGRAM MAY HAVE CONTRIBUTED TO THE DIVERTED SUBJECTS' LOWER RECIDIVISM RATE. THE COMPARABILITY OF THE STUDY GROUPS MAY HAVE BEEN AFFECTED BY SUCH THINGS AS NEW LAWS, POLICY CHANGES, AND VARIANCE IN THE PRACTICES OF CRIMINAL JUSTICE AGENCIES. SUPPORTING DATA AND A COPY OF THE CALIFORNIA DRUG DIVERSION STATUTE ARE PROVIDED. (LKM)