Everyone who runs a youth program believes in their hearts that their program helps kids, but in their heads, they know they need convincing data to prove it. This guide--updated from 2011--is here to help them get the data they need. The guide addresses a common problem throughout the youth field: Out-of-school time (OST) programs can help youth develop skills and attributes they need to be ready for college, work, and life--skills and attributes like communications, relationships and collaboration, critical thinking and decision making, and initiative and self-direction. Few OST programs have the tools to effectively measure those outcomes. Finding the right one can be daunting. This document reviews ten youth outcome measurement tools that are appropriate for use in after-school and other settings. For each tool, it provides sample items and crucial information about usability, cost, and evidence of reliability and validity. This guide--a companion to the "Forum's Measuring Youth Program Quality"--can help providers select conceptually grounded, psychometrically sound measures appropriate for programs that serve upper-elementary- through high school-aged youth. The following are appended: (1) Psychometrics: What are They and Why are They Useful?; and (2) Framework & Criteria Used to Evaluate Reliability & Validity Evidence.