Has the elementary and secondary teaching force changed in recent years? If so, how? Have the types and kinds of individuals going into teaching changed? Have the demographic characteristics of those working in classrooms altered? To answer these questions, the authors embarked on an exploratory research project to try to discover what trends and changes have, or have not, occurred in the teaching force over the past few decades. To explore these questions, the authors used the largest and most comprehensive source of data on teachers available--the Schools and Staffing Survey (SASS) and its supplement, the Teacher Follow-Up Survey (TFS). The data was used to explore what changes have taken place in the teaching force and teaching occupation over the two and a half decades from 1987 to 2012. The seven most popular trends and changes show the teaching force to be: (1) larger; (2) grayer; (3) greener; (4) more female; (5) more diverse, by race-ethnicity; (6) consistent in academic ability; and (7) less stable. For each of the trends, two large questions arise: (1) Why? What are the reasons for and sources of the trend?; and (2) So what? What difference does it make? What are the implications and consequences of the trend? In the initial edition of this report, released in November 2012, the analyses went up to 2008--the most current data then available. With the recent release of the 2011-12 SASS data, almost all of the findings for this new edition of the report have been updated. This report draws from a preliminary article published in "Educational Leadership" in May 2010 (Ingersoll & Merrill 2010). Support for some of the preliminary work on this project done in 2009-10 came from a grant from the National Commission on Teaching and America's Future, funded by the Gates Foundation. [For the preliminary article, "Who's Teaching Our Children?" (2010), see EJ896444.]