This chapter examines the factors that influence continued participation by sample members in longitudinal surveys. It is structured into two distinct parts. First, evidence from previous research that has modeled the response process within a multivariate framework is reviewed. Second, estimates of predictors of response from a new national household panel survey-the Household, Income and Labour Dynamics in Australia (HILDA) Survey-are presented. Following other recent treatments in the literature, the estimation model treats survey participation as involving two sequential events, contact and response.