How does the U.S. balance privacy with national security? This study analyzes how the three regulatory regimes of information collection for (1) criminal investigations, (2) foreign intelligence gathering, and (3) cybersecurity have balanced privacy with national security over a 50-year period. A longitudinal, arena-based analysis is conducted of policies (N=63) introduced between 1968 and 2018 to determine how policy processes harm, compromise, or complement privacy and national security. The study considers the roles of context, process, actor variance, and commercial interests in these policy constructions. Analysis over time reveals that policy actors’ instrumental use of technological contexts and invocations of security crises and privacy scandals have influenced policy changes. Analysis across policy arenas shows that actor variance and levels of transparency in the process shape policy outcomes and highlights the conflicting roles of commercial interests in favor of and in opposition to privacy safeguards. While the existing literature does address these relationships, it mostly focuses on one of the three regulatory regimes over a limited period. Considering these regimes together, the article uses a comparative process-tracing analysis to show how and explain why policy processes dynamically construct different kinds of security-privacy relationships across time and space.