Abstract  The purpose of this article is to demonstrate constraining the nominal response model inMplussoftware to calibrate data under the partial credit model (PCM) and generalized partial credit
model (GPCM). Currently, many researchers are uncertain if the PCM and GPCM can be
estimated within Mplus. Through model constraint commands in Mplus, we demonstrate that
both models can be estimated in recent versions of this software. We present an example of
this approach with data from 522 respondents on a subset of items from the Math Self-Efficacy
Scale (Betz & Hackett, 1983). It is demonstrated that the presented model code is a viable way
of estimating the models inMplus.
Keywords: generalized partial credit model, Mplus, nominal response model, partial credit
model