AbstractExisting measures of article and journal impact count citations that articles receive in other articles. Such metrics ignore citations that articles receive in monographs and edited-volume chapters. Counting article citations in books reveals that popular measures of article and journal impact discriminate against articles and journals that receive citations in books rather than (or in addition to) citations in other articles, thereby discriminating against the research contributions of scholars who publish such articles. Analysis of citation patterns over 25 years reveals that citations in books have declined in American politics research while citations in articles have increased; citations in both books and articles remain important in the other subfields. Findings suggest that political scientists should supplement indicators of journal impact based on citations in peer-reviewed articles with measures that account for the citations that published articles receive in books.