FOLLOWING A HISTORY OF LAWS AGAINST INCEST IN ENGLAND AND WALES, THE PROBLEMS WHICH SURROUND REPORTING, PROSECUTION, AND TREATMENT OF OFFENDERS ARE COMMENTED UPON. A COMPARISON WITH OTHER COUNTRIES FINDS THAT EVEN AMONG THE NATIONS OF THE UNITED KINGDOM AND AMONG THE STATES OF THE UNITED STATES THERE ARE WIDE VARIATIONS IN THE DEGREE OF RELATIONSHIP WHICH IS CONSIDERED INCESTUOUS AND IN THE LEGAL RESPONSE. IN ENGLAND THE RESPONSE IS USUALLY THE INITIATION OF FORMAL CRIMINAL PROCEEDINGS WITH THE POLICE AND THE DIRECTOR OF PUBLIC PROSECUTIONS HANDLING THE CASE. IN NEW YORK STATE THE FAMILY COURT OFTEN HANDLES INCEST, WITH THE OPTION OF REFERRING THE CASE TO CRIMINAL COURT IF THIS SEEMS JUSTIFIED. IN ENGLAND A MAN CONVICTED OF COMMITTING INCEST IS MORE LIKELY TO BE SENTENCED TO PRISON THAN IS ANY OTHER CLASS OF OFFENDER. THE EXPERIENCES OF THE CALIFORNIA CHILD SEXUAL ABUSE TREATMENT PROGRAM ARE REVIEWED. THE THEORETICAL BASIS OF INCEST LAWS IS EXAMINED. MOST ORIGINATED IN RELIGIOUS PROHIBITIONS. ANOTHER STRONG MOTIVATION IS A FEAR THAT THE CHILD OF SUCH UNIONS IS MORE LIKELY TO BE DEFORMED. A SWEDISH STUDY INDICATES THAT THIS FEAR HAS LITTLE MEDICAL BASIS. STILL ANOTHER RATIONALE, THE PROTECTION OF THE CHILDREN IN A FAMILY, IS SEEN AS THE MOST VIABLE LEGAL THEORY. DIFFERENCES IN PROSECUTION ALREADY REFLECT SOCIETY'S VIEW THAT INCEST BETWEEN AN ADULT AND A YOUNG CHILD IS MORE SERIOUS THAN INCEST BETWEEN TWO ADULTS. IT IS RECOMMENDED THAT INCEST LAWS BE REWRITTEN AS CHILD PROTECTION LAWS, WITH SPECIAL ATTENTION GIVEN TO PROTECTION OF GIRLS BETWEEN 16 AND 18. SOCIAL INTERVENTION SHOULD BE PART OF THE LEGAL RESPONSE. APPENDED MATERIALS INCLUDE STATISTICS ON INCEST IN ENGLAND AND EXTENSIVE REFERENCES. (GLR)