For over two decades, Giselle O. Martin-Kniep and her colleagues have worked for Learner-Centered Initiatives, a consulting organization based in New York, promoting best practices in curriculum, development, assessment, and leadership. A significant portion of their work is directed toward helping educators attend to and assess students' ability to communicate, collaborate, think deeply, and apply and reflect on what they know and can do. Inspired by their understanding of assessment for and as learning, they design professional learning with embedded assessment opportunities that enable participants to assess their growth and attainment of the very outcomes they are acquiring as they are learning and, in some cases, determine the impact of their learning on others. This article draws on a professional experience with about 50 teachers and administrators from 10 school districts in New York, New Jersey, and Connecticut over four full-day sessions between December 2015 and February 2016. These educators sought to learn about and assess critical thinking, metacognition, and problem solving. They worked collaboratively in small teams, first to uncover their understandings of these outcomes, then to determine what to assess and what metrics to use and, finally, to engage in peer reviews as they completed different drafts of their work. Such collaborative work enabled them to draft and, in many cases, field-test 22 assessment tools aimed at evaluating or promoting these outcomes, including learning progressions, checklists, and rubrics. This professional learning experience illustrates how program- or curriculum-embedded assessment can help facilitators and learners document their learning while revealing the inherent complexities of assessing hard-to-measure learning outcomes.