Abstract: This study combines qualitative and quantitative methods, with particular emphasis on network data of worker behavior, to analyze changes in worker communication patterns during the first three years of a post-acquisition integration. The findings suggest that new communication routines develop slowly and are not entirely enduring even when a transformative event, such as an acquisition, occurs. The level of communication between target and acquiring firm workers, as well as the position of target firm workers in their communication networks, exhibits an inverse U shape. Communication between workers across firms was greater when workers’ tasks were interdependent than when they were not interdependent. Overall, this study demonstrates that communication routines persist even when a transformative event occurs. It also illustrates the promise of using social network methods and communication log data to study social phenomena of strategic interest.