A TOTAL OF 539 PERSONS WHO NEEDED PSYCHIATRIC TREATMENT WERE IDENTIFIED IN THE KING COUNTY JAIL AND THE SEATTLE CITY JAIL, BOTH IN SEATTLE, WASHINGTON, FROM SEPTEMBER 1, 1973 THROUGH AUGUST 31, 1974. A TOTAL OF 434 MEN AND 105 WOMEN WERE EXAMINED DURING THE 2-YEAR PERIOD. OF THOSE, 296 HAD BEEN CHARGED WITH MISDEMEANORS, AND 228 HAD BEEN CHARGED WITH FELONIES; IN 15 CASES, THE CHARGES WERE NOT KNOWN. THE MEDICAL STAFF REFERRED 203 (38 PERCENT) OF THE INMATES FOR PSYCHIATRIC TREATMENT; THE CUSTODY STAFF MADE 133 (25 PERCENT) OF THE REFERRALS, WHILE THE SOCIAL SERVICE STAFF MADE 112 (21 PERCENT) OF THE REFERRALS. SOURCES OUTSIDE THE JAIL REFERRED 44 OF THE PATIENTS, AND OTHER INMATES REFERRED 29 OF THE PATIENTS. NO INFORMATION ON THE SOURCE OF REFERRAL WAS AVAILABLE ON 18 OF THE PATIENTS. ALMOST ONE-THIRD OF THE PATIENTS WERE TREATED WITHIN 24 HOURS AFTER BOOKING. IT IS ESTIMATED THAT ALMOST 50 PERCENT OF THE INMATES COULD HAVE BEEN EVALUATED WITHIN 24 HOURS IF MORE PSYCHIATRIC MANPOWER HAD BEEN AVAILABLE AND BETTER COMMUNICATION HAD EXISTED BETWEEN CUSTODY AND MEDICAL STAFF. FORTY-NINE PERCENT OF THE PATIENTS WERE DIAGNOSED AS HAVING A PSYCHOTIC DISORDER, EITHER MANIA OR SCHIZOPHRENIA. ANTISOCIAL PERSONALITY, ALCOHOLISM, AND DRUG DEPENDENCY WERE PRESENT IN 27 PERCENT, 20 PERCENT, AND 23 PERCENT OF THE CASES, RESPECTIVELY. DEPRESSION WAS DIAGNOSED IN 10 PERCENT OF THE CASES. CONTACT WITH OUT-OF-JAIL TREATMENT RESOURCES OCCURRED IN TWO-THIRDS OF THE CASES. ESSENTIALLY, CONTACT WAS LIMITED TO MEDICAL RESOURCES AND PATIENT ADVOCATES, SUCH AS FAMILY AND ATTORNEYS. TREATMENT IN A LARGE NUMBER OF CASES NECESSITATED CONSULTATION WITH CUSTODY OFFICERS, ENVIRONMENTAL MANIPULATION WITHIN THE JAIL, AND ANTIPSYCHOTIC MEDICATION. ONLY 14 PERCENT OF THE PATIENTS RECEIVED CONVENTIONAL PSYCHOTHERAPY CONSISTING OF 3 OR MORE SESSIONS. ELEVEN PERCENT OF THE PATIENTS WERE HELPED TO SECURE A VOLUNTARY TRANSFER TO A PSYCHIATRIC HOSPITAL. IT IS CONCLUDED THAT A CLOSE WORKING RELATIONSHIP BETWEEN THE MEDICAL STAFF AND THE NONMEDICAL JAIL STAFF IS CRITICAL IN SUCCESSFULLY IMPLEMENTING AN EARLY DIAGNOSTIC AND TREATMENT SERVICE. THE CUSTODY AND SOCIAL SERVICE STAFF ARE CONSIDERED TO PROVIDE AN IMPORTANT FORMAL AND INFORMAL COMMUNICATION LINK BETWEEN INMATES AND THE MEDICAL STAFF. THE STUDY DATA ARE REPORTED IN TABULAR FORM.