One-fourth of all ninth graders in the United States will not graduate from high school within four years, despite the fact that the 21st Century workplace requires more advanced knowledge and skills than ever before. Recognizing the need for a comprehensive strategy to keep teens in school and ensure that they graduate prepared for the future, AT&T awarded United Way Worldwide a contribution to start a new initiative--Family Engagement for High School Success (FEHS). This AT&T-supported initiative offered an invaluable opportunity to pioneer strategies for bringing families, school leaders, community partners, and students together to build a network of supports to keep students on the path to high school graduation, college or advanced training, and successful lives beyond. Through this initiative, United Way Worldwide supported 15 local United Way pilot sites in a planning process through which stakeholders worked together to create action plans to guide their initiatives' implementation. The planning process adopted an outcome-focused approach with the aim of designing family engagement strategies that would remove obstacles and build stronger connections between families and schools. Culled from the lessons learned throughout this process, the Family Engagement for High School Success Toolkit is designed to help those seeking to develop an informed and targeted family engagement project for high school students. It is important to note that this toolkit is based on an initiative that deliberately focused on improving academic outcomes for students at high risk of not graduating from high school. While not designed to provide guidance for the development of general family engagement strategies, the planning and implementation principles contained in the toolkit can be applied to a wide range of family engagement initiatives that focus on a broader range of student groups. The toolkit is comprised of two parts: Part I focuses on the comprehensive planning that goes into the development of a family engagement initiative, and Part II focuses on the early implementation process. Appended are: (1) Profiles of "Family Engagement for High School Success" pilot sites; (2) Checklists for planning and implementing family engagement initiative; (3) Tables and Workbooks; (4) Developing a Logic Model; (5) Data Collection Methods; and (6) Family Engagement for High School Success Year-End Summary. Individual sections contain footnotes. (Contains 2 figures and 23 tables.)