THE NEED FOR INCREASED UNDERSTANDING OF THE RELATIONSHIP BETWEEN CLIENTS AND THEIR SOCIAL SETTINGS IS SPELLED OUT. PROBATION STUDIES AND OTHER BEHAVIOR RESEARCH HAVE FOUND THAT SUPPORT AT HOME, A SUPPORTIVE ENVIRONMENT AT WORK OR SCHOOL, AND THE EXTENT OF 'CRIME CONTAMINATION' HAVE FAR MORE EFFECT ON RECIDIVISM RATES THAN PAROLE OFFICERS' EFFORT. ONE SUCH STUDY, CONDUCTED IN GREAT BRITAIN, IS SUMMARIZED. THE DEVELOPMENT OF AN INDEX TO MEASURE THOSE 3 FACTORS IS DESCRIBED. ITS PREDICTIVE POSSIBILITIES ARE ASSESSED; THE FACTORS CORRELATED SIGNIFICANTLY WITH PROBATION SUCCESS OR FAILURE. USE OF THE INDEX WITH THE JESNESS INVENTORY FOR PERSONALITY ASSESSMENT IS EXPLAINED. A TABLE SHOWS THE RESULTS OF THE TEST OF THE INDEX ON 246 YOUNG MALE PROBATIONERS. THE FACT THAT ENVIRONMENT INTERACTS SO STRONGLY WITH PERSONALITY, AS MEASURED BY THESE INSTRUMENTS, SUGGESTS THAT PROBATION OFFICERS AND COURT OFFICIALS NEED TO APPLY SYSTEMS THEORY TO THEIR WORK. TO DATE MOST SYSTEMS ANALYSIS HAS BEEN CONFINED TO LARGE ORGANIZATIONS. HOWEVER, EACH INDIVIDUAL IS PART OF ONE'S OWN SOCIAL SYSTEM. THE PROBATION OFFICER MUST RECOGNIZE THAT A 15-30 MINUTE CONTACT ONCE A WEEK IS NOT A MAJOR INFLUENCE IN THE PROBATIONER'S SYSTEM, NOR IS THE PROBATIONER AT THE HEART OF THE PROBATION OFFICER'S SYSTEM. THE REALITY OF THE SITUATION MUST BE FACED, AND THE PAROLE OFFICER MUST REDEFINE THE TASK OF DEALING WITH PROBATIONERS. INSTEAD OF CHANGING THE PROBATIONER'S PERSON, EFFORTS MUST BE MADE TO CHANGE THE PERSON'S SOCIAL SYSTEM. MANY SOCIAL WORKERS UNDERSTAND THIS INSTINCTIVELY; SOME SOCIAL WORKERS HAVE LEFT INDIVIDUAL COUNSELING AND ARE DEVOTING THEIR EFFORTS TO COMMUNITY DEVELOPMENT WITH THE GOAL OF REDUCING CRIME. THE TENSION BETWEEN PERCEPTION OF THE PROBATION SYSTEM AS SOCIAL WORK, AND AS CORRECTIONS IS NOTED. THE FOUR CONCEPTUAL LEVELS OF RELATIONSHIP (CAUSAL TEXTURING) WITH A PROBATIONER ARE EXAMINED. THERAPY AT EACH LEVEL IS DESCRIBED WITH ATTENTION TO THE PROBATION OFFICER'S STRATEGIC TREATMENT CHOICES. THESE FOUR LEVELS ARE PROPOSED AS THE STRUCTURE OF AN ENVIRONMENTAL SYSTEMS THEORY. TO TRULY EFFECT CHANGE IN A PROBATIONER, THE OFFICER/CLIENT RELATIONSHIP MUST BE DEEP ENOUGH TO EFFECT A CHANGE IN THE OFFENDER'S SOCIAL SYSTEM AND HIS PLACE IN IT. DEVELOPMENT OF AN ENVIRONMENTAL SYSTEMS THEORY IS NEEDED TO CHALLENGE, CLARIFY, AND BUILD ON THE PRESENT ASSUMPTIONS MADE IN SOCIAL WORK. THE ARTICLE IS FOOTNOTED.