DEMOGRAPHIC DATA SHOW THAT WOMEN ARE LESS LIKELY THAN MEN TO KILL THEIR SPOUSES, THAT MOST RESPONDENTS HAD RELATIVELY LITTLE SCHOOLING AND HELD UNSKILLED OR SEMISKILLED JOBS, AND THAT COMMON LAW MARRIAGES ARE MORE LIKELY TO TERMINATE EARLIER IN LETHAL VIOLENCE THAN ARE LEGAL MARRIAGES. ECONOMIC PRESSURES APPEAR NOT TO BE RELEVANT FACTORS IN LETHAL VIOLENCE BETWEEN SPOUSES. PROCESSES AND EVENTS LEADING TO INTERSPOUSE HOMICIDE -- THE ACTOR'S LIFE EXPERIENCES AND CIRCUMSTANCES, THE MARITAL RELATIONSHIP AND CONFLICTS, AND THE STRUCTURING OF THE VIOLENT SITUATION -- ARE TRACED, AND A MODEL DESCRIBING BOTH HISTORICAL/BACKGROUND AND SITUATIONAL/IMMEDIATE ELEMENTS IN LETHAL VIOLENCE BETWEEN SPOUSES IS DEVELOPED. EARLY LIFE EXPERIENCES THAT CAN PREDISPOSE PEOPLE TO VIOLENT BEHAVIOR IN THEIR MARRIAGES INCLUDE UNSATISFACTORY OR FRUSTRATING RELATIONSHIPS WITH PARENTS AND THE LEARNING OF VIOLENT REACTIONS. STUDY FINDINGS INDICATE THAT SPOUSE KILLINGS TEND NOT TO BE SUDDEN, UNANTICIPATED OUTBURSTS OF RAGE. IN MOST CASES, THE MURDER WAS THE ENDPOINT OF A SERIES OF QUARRELS OVER EXTRA-MARITAL AFFAIRS OR SEXUAL REFUSALS, TEMPORARY SEPARATIONS, PREVIOUS PHYSICAL FIGHTS, AND HEAVY DRINKING BY BOTH OFFENDER AND VICTIM (PARTICULARLY AT THE TIME OF THE FATAL ACT). IT IS THEORIZED THAT A PERSON WHO HAS LONG BEEN THREATENED OR ABUSED IN SOME WAY BY HIS OR HER SPOUSE REACHES A POINT WHEN THE ABUSE IS NO LONGER TOLERABLE. AT THIS POINT, THE THREATENED PARTY ENTERS A MENTAL STATE REFERRED TO AS ENCAPSULATION, IN WHICH RESTRAINT AND FUTURE-ORIENTED THOUGHTS ARE REPLACED BY SEIZING UPON SIMPLE, IMMEDIATE, OFTEN VIOLENT SOLUTIONS. ENCAPSULATION IS FACILITATED BY INTOXICATION AND BY THE ABSENCE OF PERSONS WITH INTERVENING CAPABILITY. IMPLICATIONS OF THESE AND OTHER FINDINGS FOR PREVENTION OF INTERSPOUSE VIOLENCE ARE DISCUSSED. CASE STUDIES, SUPPORTING DATA, STUDY INSTRUMENTS, AND A LIST OF REFERENCES ARE INCLUDED. (LKM)