Primary data sources included the Supplementary Homicide Report on domestic homicides, police log calls for service, qualitative interviews with police officers who handled domestic violence calls, and incident code forms filled out by police officers who responded to domestic violence calls. Most police agencies in Massachusetts used standardized incident coding forms. Data revealed that 86 percent of domestic violence calls involved male offenders. Some type of weapon was involved in 41 percent of domestic violence cases. The most common weapons were hands, fists, or feet; knives were used in 4.3 percent of cases, followed by blunt objects (1.4 percent) and guns (1 percent). The most frequent resolution of domestic violence calls involved advising victims of their rights. Police arrests in only 7.7 percent of cases were based on such factors as repeat call, court order violation, presence of a witness, weapon involvement, disturbance location, offender race, violence seriousness, and victim preference. Most domestic violence cases were not resolved by arresting the alleged perpetrator. Arguments for and against mandatory police arrests in domestic violence cases are examined. 26 references, 1 note, and 5 tables