Firearm injury is a major public health burden in the US, and yet there is no single, validated national data source to study community firearm violence, including firearm homicide and nonfatal shootings that result from interpersonal violence. To assess the validity of the Gun Violence Archive as a source of data on events of community firearm violence and to examine the characteristics of individuals injured in shootings. This cross-sectional observational study compared data on community firearm violence from the Gun Violence Archive with publicly available police department data, which were assumed to be the reference standard, between January 1, 2015, and December 31, 2020. Cities included in the study (Philadelphia, Pennsylvania; New York, New York; Chicago, Illinois; and Cincinnati, Ohio) had a population of greater than 300 000 people according to the 2020 US Census and had publicly available shooting data from the city police department. A large city was defined as having a population greater than or equal to 500 000 (ie, Philadelphia, New York City, and Chicago). Data analysis was performed in December 2022. Events of community firearm violence from the Gun Violence Archive were matched to police department shootings by date and location. The sensitivity and positive predictive value of the data were calculated (0.9-1.0, excellent; 0.8-0.9, good; 0.7-0.8, fair; 0.6-0.7, poor; and <0.6, failed). A total of 26 679 and 32 588 shooting events were documented in the Gun Violence Archive and the police department databases, respectively, during the study period. The overall sensitivity of the Gun Violence Archive over the 6-year period was 81.1%, and the positive predictive value was 99.0%. The sensitivity steadily improved over time. Shootings involving multiple individuals and those involving women and children were less likely to be missing from the Gun Violence Archive, suggesting a systematic missingness. These findings support the use of the Gun Violence Archive in large cities for research requiring its unique advantages (ie, spatial resolution, timeliness, and geographic coverage), albeit with caution regarding a more granular examination of epidemiology given its apparent bias toward shootings involving multiple persons and those involving women and children.