Developing psychometrically sound instruments can be difficult, especially if little is known about the constructs of interest. When constructs of interest are unclear, a mixed methods approach can be useful. Qualitative inquiry can be used to explore a construct’s meaning in a way that informs item writing and allows the strengths of one analysis method to compensate for the weaknesses of the other. Mixing method applications can be complex, however, there are few examples within the literature pertaining to the mix of interviews, Rasch modeling, and classical test theory. This article demonstrates how to mix qualitative inquiry with Rasch modeling (and classical test theory) in order to develop an instrument that measures a complex construct: patient trust.