IN THE CONTEMPORARY LEGAL SYSTEM OF THE SOUTH NYANZA DISTRICT WHERE THE GUSII LIVE, SEX OFFENSES ARE CLASSIFIED AS RAPE OR INDECENT ASSAULT ACCORDING TO WHETHER THE VICTIM'S VIRGINITY AT THE TIME OF THE OFFENSE CAN BE ESTABLISHED. AN EXTREMELY CONSERVATIVE ESTIMATE OF THE ANNUAL RATE OF SEX OFFENSE INDICTMENTS BASED ON COURT RECORDS FOR 1955 AND 1956 YIELDS THE FIGURE OF 47.2 PER 100,000 POPULATION, COMPARED TO A RATE OF 13.85 PER 100,000 IN U.S. URBAN AREAS DURING THE SAME TIME PERIOD. THE GUSII'S INSTITUTIONALIZED FORMS OF SEX ANTAGONISM, RELATED TO PATTERNS OF INTERCLAN HOSTILITY, ARE NOT MITIGATED BY THE CUSTOM OF INTERCLAN MARRIAGE. BETWEEN THE GUSII, LEGITIMATE HETEROSEXUAL ENCOUNTERS WITHIN MARRIAGE ARE AGGRESSIVE CONTESTS, INVOLVING MALE FORCE AND FEMALE RESISTANCE WITH AN EMPHASIS ON THE PAIN INFLICTED BY THE MALE ON THE FEMALE; UNDER CIRCUMSTANCES THAT ARE NOT LEGITIMATE, SUCH OCCURRENCES COULD BE TERMED RAPE. STRONG SUPERNATURAL AND TRIBAL SANCTIONS ENFORCE MARITAL FIDELITY, AND OTHER OUTLETS FOR MALES POSSIBLE WITHIN THE LOCAL CLAN (MASTURBATION, HOMOSEXUALITY, AND BESTIALITY) ARE EXTREMELY RARE OR SOCIALLY FORBIDDEN. THE TRADITIONAL SYSTEM OF CONTROLLING INTERCLAN SEXUAL BEHAVIOR THROUGH MILITARY DETERRENCE AND TERRITORIAL SEPARATION WAS ELIMINATED WITH THE ARRIVAL OF THE BRITISH ADMINISTRATION IN 1907. THREE TYPES OF RAPE ARE DISTINGUISHED: RAPE RESULTING FROM SEDUCTION, PREMEDITATED SEXUAL ASSAULT, AND ABDUCTION. THE LATTER IS DIRECTLY RELATED TO THE ECONOMIC CONCEPT OF 'BRIDEWEALTH' IN THAT YOUNG MEN WHO CANNOT AFFORD THE REQUIRED PAYMENT (LIVESTOCK) OCCASIONALLY RESORT TO ABDUCTING GIRLS FOR WIVES. FOUR FACTORS IN THE GUSII SITUATION WHICH COULD BE FOUND IN ANY SOCIETY WITH A HIGH INCIDENCE OF RAPE ARE TO BE ASCERTAINED FROM THIS STUDY: (1) SEVERE FORMAL RESTRICTIONS ON THE NONMARITAL SEXUAL RELATIONS OF FEMALES; (2) MODERATELY STRONG SEXUAL INHIBITIONS ON THE PART OF FEMALES; (3) ECONOMIC OR OTHER BARRIERS TO MARRIAGE WHICH PROLONG THE BACHELORHOOD OF SOME MALES; AND (4) THE ABSENCE OF PHYSICAL SEGREGATION OF THE SEXES. THE CONCEPTS OF STRUCTURAL BARRIERS AND SOCIAL INHIBITIONS ARE EXAMINED FROM A UNIVERSAL VIEWPOINT, AND THE AUTHOR INDICATES THAT IMPLICATIONS EXIST FOR THE STUDY OF CONTEMPORARY CULTURAL CHANGE AND THE BREAKDOWN OF TRADITIONAL CONTROLS OF SEXUAL BEHAVIOR IN MANY PARTS OF THE WORLD.