Maturity models fill the need for a measure of overall growth in how outcomes assessment is defined and how feedback informs improvement to meet internal and external expectations at individual institutions of higher education. An exploratory qualitative study was conducted to develop an instrument, the Assessment System Maturity Matrix (ASMM), to observe and evaluate outcomes assessment system maturity. Research procedures included conducting a literature review and comparing business, software, and limited education maturity models; administering self-reported questionnaires to higher education outcomes assessment professionals; and piloting the instrument. Data collection results provided the ideal criteria for the ASMM design and content and led to ASMM development and refinement. Some deviation from the established maturity order sequence of plan, build, implement, and evaluate was noted. The ASMM can enable diverse institutions of higher education to focus on current assessment practice maturity efficiently to determine subsequent actions to improve outcomes assessment performance. Further research is required to explore the awareness and development of outcomes assessment system maturity awareness among the various types of institutions within the higher education community.