This third edition provides a review of developmental, ecosystemic, and career theories to inform relevant P–12 career and college readiness interventions. It reviews numerous developmental theories and assists readers in using them as a foundation to design sequential and developmentally appropriate career and college readiness curricula and interventions. The book help readers understand the ecosystemic influences (e.g., family, school, community, society) on career development and college readiness, and discusses both why it is important to involve various stakeholders in career and college readiness initiatives and how to involve them. It starts with six foundational chapters in which it reviews (a) current data and issues related to college and career readiness, (b) information to assist with postsecondary planning and career and college advising, (c) professional preparation standards for individuals who will provide career and college readiness interventions, (d) cultural considerations in career and college readiness, (e) career and college readiness assessment, and (f) career and college readiness curriculum development. It addresses career development and college readiness needs by grade level. The focus in each grade level chapter is to identify common tasks that occur at that level and to help readers apply knowledge of ecosystems, developmental theories, and career theories, and identify ways that multiple stakeholders can become involved in career and college readiness interventions. This third edition has been revised and includes: updated workforce statistics; work-based learning opportunities for secondary students; the impact of social media on student development; career and technical education pathways; gap year information; enhanced instructor's manual, including project-based activities, discussion prompts, and related online activities, games, and apps. This book helps both preserves and practicing school counselors to identify career and college readiness needs and design developmentally appropriate interventions that are grounded in theory and research.