A pervasive challenge for Wisconsin and states across the nation is accurate assessment of teacher labor supplies at the state and local levels. Demand measures based on predictions of changing teacher and student demographics have been wildly inaccurate. This report presents findings on key features of the Wisconsin teacher labor market, including mobility, attrition, supply, and demand. The authors use data from multiple sources (including state staffing and credentialing files, application and vacancy information, and statewide survey data on perceptions of staffing challenges) to: (1) establish a common vocabulary around categories of labor supply--specifically which positions are high supply, which are medium supply, and which are low supply; (2) provide a baseline against which subsequent reports can build and future policies can be assessed; (3) provide a common base of empirical evidence to focus and foster debate; and (4) identify aspects of the teacher labor market that are problematic. This report provides evidence on teacher supply and demand in Wisconsin to help policymakers see which avenues are available to influence the complex dynamics of differential mobility, attrition, licensure, and selection across educator labor markets. This portrait of Wisconsin's teacher labor market illustrates and defines key features to create a common understanding and vocabulary to engage emerging and persistent challenges. The authors organized this report around the following questions: (1) What are the prevailing trends in teacher attrition and mobility?; (2) What is the current supply of teachers?; (3) How are districts responding to staffing challenges?; and (4) Is there a teacher shortage in Wisconsin?