In recent years media portrayals of teachers’ unions have grown increasingly negative (Goldstein, 2011) and policymakers at all levels of government have proposed, and in many cases passed, legislation that weakens teachers’ unions and removes traditional union protections. In particular, the collective bargaining agreements (contracts, or CBAs) unions negotiate with local school districts are facing increasing scrutiny. In just the last four years three states have removed teachers’ unions’ express rights to collectively bargain and two additional states have prohibited collective bargaining altogether (NCTQ, 2014). CBAs are the topic of so much debate and policy action because they contain policies and regulations that dictate aspects of education policy in every facet of the school and district workplace. If the policies negotiated into these CBAs restrict administrators from acting in ways that improve student achievement, then collective bargaining should be curtailed. However, if CBAs protect teachers and, as a result, improve teacher recruitment, retention and performance, then CBAs and the policies within them should be left to local negotiations. Although this debate is increasingly being played out in the public arena through legislation and court rulings, there has been relatively little attention given to the actual contents and impacts of CBAs in the research literature. The three papers in this panel present the most recent empirical research about the impact of CBAs on relevant district outcomes from three states with diverse policy contexts: California, Washington and Florida. In the first paper in this panel, Strunk provides the first longitudinal examination of CBAs based on a panel of teachers’ union contracts. She assesses how changes in contract strength and contract provisions are associated with changes in student achievement outcomes. She finds that, in California, changes in contract strength are not significantly associated with changes in student outcomes on average or at any point in the achievement distribution. The next two papers in the panel focus on the role of teachers’ seniority in voluntary and involuntary teacher transfers. These CBA provisions are particularly important because seniority transfer protections may contribute to the inequitable distribution of teachers across schools within districts (Moe, 2005; Anzia & Moe, 2014). In the panel’s second paper, Goldhaber shows that CBAs in Washington that specify seniority as the only factor in voluntary teacher transfer decisions exacerbate patterns of teacher exits from high-minority schools and contribute to teacher turnover from high-need schools. Although this result may be concerning from an equity perspective, Feng et al. show in the panel’s final paper that in Florida the teacher quality gap (measured by average teacher value-add) between more and less advantaged schools is no wider in districts where seniority guides transfer decisions. The session chair is the Director of Policy for a major education reform organization that focuses on education personnel and governance issues. She will open the session with a brief overview of current federal and state policy attention focused on teachers’ unions and their contracts. The discussant will address the implications of the three studies for future research and policy.