The Stanford Child Custody Study (Study I) is a three wave, longitudinal study of post-separation child custody arrangements in a sample of 1,124 families who filed for divorce in two California counties. All parents filed for divorce in either San Mateo or Santa Clara Counties between September 1984 and April 1985, and all had at least one child under the age of 16 at the outset of the study. Three separate telephone interviews were conducted with parents over a three-year period. Additional information was drawn from court records to determine the sequence of legal events and their relationship to the day-to-day lives of families. The study's longitudinal design serves to clarify several basic processes associated with divorce, including: 1) the evolution and maintenance of residence and visitation arrangements; 2) the legal process leading to settlement; 3) the degree of conflict and cooperation between divorced parents; 4) disengagement or continued involvement of the non-custodial parent; 5) compliance with legal and informal agreements; 6) family reorganization; and 7) remarriage.