Competency-based education in K-12, postsecondary, and the workforce is based on the mastery of skills, rather than age, seat time, or hours. Learners demonstrate competencies that align with standards and industry needs. It has transformed learning in many fields, particularly STEM. Competency-based microcredentials provide recognition of skill attainment after the learner has demonstrated mastery through competency-based assessments. Competency-based STEM microcredentials recognize learners for their industry-aligned skills, demonstrating proficiency in critical STEM competencies, bridging skill gaps, and enhancing employability in a rapidly evolving workforce. This chapter explores the components of high-quality competency-based assessment frameworks for STEM microcredentials that ensure the quality assurance needed to develop STEM pipelines from K-12 to postsecondary education and the workforce. Additionally, this chapter discusses challenges with implementing successful competency-based STEM microcredentials, as well as offers recommendations for addressing these challenges.