Abstract: A quality control device for microscope slide staining assays and method of use are provided for assessment of the quality of reagents and the assay process of immunohistochemical, in situ hybridization, histochemical, and chromogenic assays. The quality control device includes multiple control compounds, each is immobilized on a plurality of spatially defined sites on a substrate, and each of the plurality of spatially defined sites has a different amount of the control compound. Each of the control compounds is a target of a specific reagent used in the assay.