This Statistics in Brief provides a snapshot of the state of teacher professional development activities among U.S. public school teachers using data collected through the 2011-12 Schools and Staffing Survey (SASS) Public School Teacher Questionnaire. This report relies on data provided by public school teachers about their professional development activities during the 2011-12 school year. The report focuses on public school teachers' responses to questions regarding the topics covered in their professional development activities; the amount of time spent in those activities in the last 12 months; the support they received for participation; and whether they engaged in less formal professional activities, such as working collaboratively with other teachers on instruction. The report examines each of these aspects of public school teachers' professional development not only nationwide but also by the level of the schools in which they taught, their years of teaching experience, and the locale in which they taught. The following are appended: (1) Data Tables; and (2) Standard Error Tables.