The push for accountability in public schooling has extended to the measurement of teacher performance, accelerated by federal efforts through Race to the Top. Currently, a large number of states and districts across the country are computing measures of teacher performance based on the standardized test scores of their students and using them in combination with other indicators to help categorize teachers as effective or ineffective. With the implementation of the Common Core State Standards in a majority of states and the development of specific assessments that align with them, it is particularly urgent to open up the field right now to discuss and shed light on best practices in computing teacher performance measures. The market for new assessments coupled with derivative products that compute teacher effectiveness measures--each promoting a particular methodology--is becoming increasingly competitive. Policy makers must make informed decisions on which products and procedures they will use. A research team at Michigan State and Indiana Universities has contributed a number of key insights to the body of research on best practices in computing teacher performance measures and is in the process of disseminating its findings. This paper describes the project, its findings, and its preliminary recommendations for policy. Bios of principal investigators are appended.