Attrition is the process of dropout from a panel study. Earlier studies into the determinants of attrition study respondents still in the survey and those who attrited at any given wave of data collection. In many panel surveys, the process of attrition is more subtle than being either in or out of the study. Respondents often miss out on one or more waves, but might return after that. They start off responding infrequently, but more often later in the course of the study. Using current analytical models, it is difficult to incorporate such response patterns in analyses of attrition. This article shows how to study attrition in a latent class framework. This allows the separation of different groups of respondents, that each follow a different and distinct process of attrition. Classifying attriting respondents enables us to formally test substantive theories of attrition and its effects on data accuracy more effectively.