In this chapter, we introduce the rating scale model (RSM) and the partial credit model (PCM) and illustrate their applications in language assessment research. The introduction of the models builds upon the dichotomous Rasch model. We review language assessment studies that have utilized the RSM and/or the PCM and discuss how model performance has been evaluated in the reviewed studies. We then illustrate the use of the RSM and the PCM with data collected using a questionnaire designed to measure motivation to learn and use English. We fit the RSM and the PCM to the motivation questionnaire data using Winsteps, compare the results from the two models, discuss their differences, and examine how well they approximate the data.