This seminar introduces longitudinal panel data models in Lavaan using SEM, including latent growth models (i.e., latent curve or latent trajectory models) and cross-lagged panel models (i.e., panel vector autoregression) with random and fixed effects, including the random intercept cross-lagged panel model (RI-CLPM) to assess time-varying and stable relationships. Short-run and long-run effects will be covered and methods for assessing them provided. An official Instats certificate of completion is provided at the conclusion of the seminar. For European PhD students, the seminar offers 2 ECTS Equivalent point.