The present study extends recent advances coordinating research on cognition and psychometric modeling around fractions. Recent research has demonstrated that the Diagnosing Teachers' Multiplicative Reasoning Fractions survey provides information about distinct components necessary for reasoning in terms of quantities when solving fraction arithmetic problems. The present study (a) adds a new component of validity for the survey and (b) examines the utility of the survey as a measure of growth in pre-service middle-grades teacher's facility with fraction arithmetic as they completed a 1-semester content course. Results provide an existence proof that that the survey is sensitive to shifts towards more proficient reasoning. [For the complete proceedings, see ED583608.]