A dataset exploring turnout patterns in Spanish party primaries (1991-2023).

The paper presents exhaustive information on a dataset of primary processes held by Spanish political parties with representation at both the national and regional level. Using evidences collected from various sources, the dataset covers more than 360 processes carried out by more than 30 Spanish political parties between 1991 and 2023, at both the national and regional level and for both candidate and leadership selection processes The dataset provides information on the results of the ballots (Turnout, Share of the winner), some basic party features (Ideology, etc.) and the specific features of each process (Competitiveness, Voting procedures, etc.