Why and when are some (minority-party) legislators more influential than others? In this impressive work, Jennifer Hayes Clark examines whether minority-party members are able to play a role as active participants in the legislative processes of their states. Are they locked out at the committee assignment, cosponsorship, floor consideration, roll call voting, or final passage stage of the legislative process? Do they receive equal treatment compared with majority-party members? What contextual factors condition these relationships?

The research design is ambitious and careful. Clark has mastered the art of crafting scripts to scrape from the multiple and various data formats maintained on state websites the information needed to tally the legislative history of all bills (and to categorize them), the roll call votes of legislators, their sponsorship activities, and much more, typically for 10 years or more per legislature. The design is also cognizant of potential data limitations. For instance, polarization is measured using elite surveys to preclude bias arising from the legislative process.

Results are remarkably robust across stages of the legislative process. Consistent with institutional theories, minority members achieve more influence when their party has stronger institutional prerogatives (for example, the right to appoint committee member