This Research Brief describes the results of an exploratory study of the development and potential uses of a set of college readiness measures for Maine high schools. The study was designed to: (1) explore the viability of creating a series of school-level college readiness indices; (2) examine the relationships between the indices and other school level input factors; and (3) explore how the indices may be used at the state and local levels in assessing college readiness of high schools' graduates. This exploratory study was done in three phases. Phase I entailed the creation of a series of potential high school-level college readiness indices. Phase II explored the relationships between these indices and how the indices may be related to each other, school poverty levels, school sizes, and other school level factors. The third and final phase of the study explored how the indices might be used statewide and at the local school district level in assessing progress in promoting and increasing levels of college readiness in Maine's high schools. Ultimately, the goal was to identify school-level indicators that support students' success in applying and securing admission to college and performing well upon enrollment. Included with the report is the appendix: High School College Readiness Indices. [This study was funded by the Maine State Legislature, and the University of Maine System.]