Lievens emphasized the extent to which new measurement tools and additional statistics can be used to advance research on trait expression across situations. We suggest that advanced psychometric models represent additional important and complementary building blocks for progress and new insights in research on trait expression across situations. Here, we offer two specific examples of this: (1) Item Response Theory modelling of within-person variability simultaneous with estimation of latent trait levels and (2) estimation of latent trait and latent situation factors from a multitrait-multimethod framework. Copyright (C) 2017 European Association of Personality Psychology