With many cities showing an interest in afterschool system building and research providing a growing body of useful information, this Wallace Perspective offers a digest of the latest thinking on how to build and sustain an afterschool system, and the challenges and opportunities that lie ahead for this promising work. The report (a follow-up to a 2008 Perspective) focuses on the four components of system building that the most current evidence and experience suggest are essential: (1) "Strong leadership from major players": There is no substitute for a committed mayor or superintendent, but for a system to thrive long term, city agencies, private funders, schools, program providers and families all need to "own" the effort to some degree; (2) "Coordination that fits local context": A system's coordinating entity can be a single public agency, multiple agencies working together, a nonprofit intermediary or a network of partners, depending on local needs; (3) "Effective use of data": Gathering and sharing data on a large scale takes both technology to track and organize information and a skilled staff to interpret and act on it; and (4) "A comprehensive approach to quality": Cities must decide what program quality means to them, how "high stakes" to make their assessments of it and how to support continuous improvement of programs. An infographic illustrates the elements and offers key facts about afterschool and systems building today. [For the 2008 report, "A Place to Grow and Learn: A Citywide Approach to Building and Sustaining Out-of-School Time Learning Opportunities. Perspective", see ED507224.]