Abstract:Research on coalitions in the policy process has found evidence of both short-term and long-term coalitions. Two possible methodological reasons for the varied results are that (1) there has been little systematic longitudinal research on the topic, and (2) most scholars have not distinguished situations where fundamental versus secondary interests are at stake. This article addresses both points by first applying the Advocacy Coalition Framework (ACF), which distinguishes fundamental from secondary beliefs/interests, and then performing a quantitative analysis of the content of organizations' testimonies regarding automotive pollution control over 26 years. Consistent with the ACF, we find that coalitions of interest groups, legislators, local governments, and agencies are relatively stable over time, despite two potentially disruptive events—the 1973–74 Oil Embargo and the 1980 Elections. On the other hand, there is little support for the ACF's hypothesis that broader beliefs will be more stable than narrower secondary beliefs. Our systematic methodology also enables us to separate the general pattern of stability from interesting exceptions of instability.