In particular, the study explored the effect of the victim-offender relationship, the quality of the physical description of the suspect available at the initial report of the crime, individual victim and suspect characteristics, and characteristics police officers used to assess the seriousness of the rape claim. The study hypothesized a combination of white victim and black suspect, a prior victim-offender relationship, police perception of a crime report as serious and credible, strength of evidence available at the time of an initial report, and victim cooperation with an investigation would increase the likelihood of arrest. Data were collected from the sexual assault investigative unit of a large municipal police department in 1995. Study results indicated the race of the victim and the suspect played no role in determining case outcomes. Among the sample of founded sexual assault cases, the probability of arrest increased when a thorough physical description was available, when there was a prior victim-offender relationship, when the reported crime included several credible indicators of offense seriousness, and when the victim agreed to a sexual assault examination. Police officers used certain information available to them when determining whether a sexual assault case was founded. Variable impacts for indicators of the strength of evidence, victim cooperation, and case seriousness are discussed. 31 references, 5 notes, and 6 tables