THE FIRST TEST PERIOD IMMEDIATELY FOLLOWED THE RECRUITS' APPOINTMENT TO THE FORCE AND THE SECOND WAS 6 MONTHS LATER. RESULTS SHOWED THAT WHEN A POLICE OFFICER REMAINS IN THE OCCUPATION FOR EVEN A RELATIVELY SHORT TIME, THERE IS A PRECIPTIOUS DROP IN HIS LEVEL OF OVERALL PROFESSIONALISM. THIS FINDING HELD FOR THREE OF THE FIVE SUBSCALE MEASURES OF PROFESSIONALISM AND WAS IN THE PREDICTED DIRECTION FOR THE OTHER TWO. USE EXPLANATION FOR THIS FINDING IS THAT WHEN A NEW RECRUIT BEGINS PATROL DUTY, HE EXPERIENCES A REALITY SHOCK FROM CONTACT WITH A PUBLIC THAT SEEMS UNAPPRECIATIVE, EVEN HOSTILE. HE THUS TURNS TO FELLOW POLICE OFFICERS FOR SUPPORT AND GUIDANCE AND THERE IS REDUCED COMMITMENT TO PROFESSIONAL GOALS. A SECOND EXPLANATION IS THAT SUCH A REALITY SHOCK MAY ALSO GENERATE DISENCHANTMENT WITHIN THE RECRUIT TOWARD THE OCCUPATION, AND HIS PROFESSIONAL COMMITMENT MAY DIMINISH. FUTURE POLICE RESEARCH SHOULD FOCUS ON DETERMINANTS OF THE REDUCTION OF PROFESSIONALISM PARTICIPANT OBSERVATION AND LONGITUDINAL STUDIES. TABLES, NOTES, AND REFERENCES ARE INCLUDED. (MJW)