Postsecondary Institutions are under pressure to explain their costs. Noninstructional administrative staff represent a significant cost and number of people working in higher education. Postsecondary institutions hire noninstructional staff in response to their specific needs related to educational activity at the institution. Past research on noninstructional staff has sought to link their size to the number of faculty or to assert that the staff's presence is an unnecessary expense. This study uses data from the IPEDS data collection at NCES to estimate staff sizes using educational metrics. To select the best subset of variables from the vast collection, an elastic net regression was run to identify what independent variables best estimate noninstructional staff size at 4-year public and private nonprofit degree-granting institutions with at least 500 FTE enrolled students. This study finds that 91% of the variance in noninstructional staff size can be accounted for by seven independent variables that are publicly available for all US institutions. This finding provides a model by which institutions may compare their noninstructional staffing levels and consider appropriate actions. It also lays the foundation for further study into noninstructional administrative staffing level trends and whether they have changed over time. The postsecondary industry may seek to understand better how some institutions can perform with less noninstructional staff. This study provides a means to determine institutions that may serve as efficiency models. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]