Black gay, bisexual, and other men who have sex with men (BMSM) are the subpopulation most disproportionately affected by HIV in the United States. Testing Makes Us Stronger (TMUS), a communication campaign designed to increase HIV testing rates among BMSM ages 18 to 44, was implemented in the United States from December 2011 through September 2015. We used interrupted time series analysis (ITSA) to compare pre- and post-campaign trends in monthly HIV testing events among the priority audience in six of the implementation cities from January 2011 through December 2014. In the 11 months prior to the launch of TMUS, HIV testing events among BMSM in the six campaign implementation cities decreased by nearly 35 tests per month (p = .021). After the introduction of TMUS, the number of HIV testing events among BMSM in the same cities increased by more than 6 tests per month (p = .002). ITSA represents a quasi-experimental technique for investigating campaign effects beyond underlying time trends when serial outcome data are available. Future evaluations can be further strengthened by incorporating a comparison group to account for the effects of history and maturation on pre- and post-campaign trends.