A growing literature examines the dynamics of social movement contention within and across "social fields." While fields tend toward stability, events and processes elsewhere in a broader system of fields can provide opportunities for movement mobilization. Most accounts see these cross-field dynamics as exogenous events, granting movements little control over when and how these opportunities might emerge. In contrast, this article argues that activists can and do purposely create cross-field effects. Examining changes in contentious practice in the American labor movement-which in recent decades, has reoriented contention over workplace issues away from workplaces themselves, and toward political arenas more traditionally dominated by community concerns-this article advances the concept of cross-field manipulation, purposive strategic action that accounts for the positioning of actors across social fields, triggering events in one field so as to reorder the dynamics of another. Using a historical study of evolving organizing practices in a Southern California hotel workers' union, including interviews and archival sources, the paper identifies three mechanisms-power analysis, alliance building, and actor-triggered crises-whereby labor activists purposely generate cross-field effects. Through repeated interactions with employers and polities, activists learned a unique campaign model that politicized workplace conflict in communities and markets, generating opportunities for workplace gains.