The concept of party identification is one of the most used indicators in election studies worldwide. However, not much is known about the meaning of party identification. This article explores why adherents identify with a political party. Based on existing notions of partisanship, a coding scheme is derived and an open-ended question from a large-N German survey is analyzed. By using Latent Class Analysis, seven meaning types of adherents are identified whose shares differ heavily by party. Most adherents base their identification either on ideological grounds or evaluative reasons, which has a meaningful impact on the parties’ possibilities for ideological change and partisan stability.