Title: Old and New Approaches for Analyzing Categorical Data in a SEM Framework Author: Yves Rosseel Abstract: In traditional software for structural equation modeling (SEM), there are two options to deal with binary and ordinal observed variables. The first option is called the three-stage limited information approach (in the Mplus world, this known as estimator WLSMV). The second option is based on the IRT tradition where full information maximum likelihood estimation is the golden standard. Recently, a new approach called pairwise maximum likelihood (PML) has been introduced in the literature. This approach uses bivariate information only, making it computationally feasible to handle large models with many observed and latent variables (unlike full ML). But PML is still rooted in the (composite) maximum likelihood framework (unlike WLSMV) and inherits many of its desirable statistical properties. In this talk, I will briefly discuss the three approaches, and their implementation in SEM software. The PML approach is currently only implemented in the R package lavaan, and serves as an example of how open-source software can foster the development of new statistical ideas.