Our field of couple and family therapy focuses on change, different ways people change, and how therapists can facilitate change. Change can be modeled as an average trajectorygrowth curve model-or as multiple classes of trajectories-growth mixture model. The field of MFT has not yet fully embraced implementing more advanced longitudinal modeling procedures to study what we care about most, change across time. To support our field moving in this direction, we provide a step-by-step description and example in Mplus software. Our example analysis used N = 5,958 participants from the Add Health dataset, to identify unique classifications of trajectories of binge drinking. We discuss how these analytical methods provide increased options to advance family science and clinical research. Studying change across time is at the heart of family science and clinical research. Family development, family processes, symptom development, and therapeutic change, are all complex, heterogeneous, and inherently longitudinal in nature. Therefore, a sophisticated approach to examine these intricacies capable of accounting for various rates of change across time is essential. Recent statistical developments can more fully reflect family and clinical dyadic processes across time, such as: autoregressive models (i.e., inter-associations across time between multiple variables), latent growth curves (LGC; average rate of change across time; Duncan, Duncan, & Strycker, 2006), and latent class growth analysis (LCGA) or growth mixture models (GMM; multiple paths of change across time; Jung & Wickrama, 2008), latent change score models (Grimm, Ram, & Estabrook, 2017), and latent transition analyses (Hawkins et al., 2017). These techniques vary in the research questions they can address and their focus. Most statistical approaches, including autoregressive models and latent growth curves, are what can be classified as "variablecentered" approaches, meaning that the population of interest is considered homogenous and that an average-level of association between variables, or an average rate of change adequately represents the data (Jung & Wickrama, 2008). Person-centered modeling, on the other hand, considers the population as heterogeneous. This type of modeling can identify groups of people that have similar response patterns to a questionnaire (e.g., latent class analysis), that membership in a subgroup can change over time (e.g., latent transition analysis), and that rates of change may vary between different groups of participants who may share common characteristics (e.g., growth mixture modeling). Growth mixture models (GMM) are a "person-centered" approach to identifying