Several concurrent trends are increasing the likelihood that short courses, microcredentials, and flexible learning pathways will become a regular and even dominant feature of education and training globally. This policy paper reflects on these trends with special reference to the post-secondary education sector, and explores ways to organize short courses and micro-credentials as effective tools for offering up-to-date, quality learning to much larger segments of the population, creating flexible learning pathways, fostering learner autonomy, and formally acknowledging competencies. The paper discusses existing definitions and proposes a universal working definition for micro-credentials developed by UNESCO. It also describes 10 challenges that potentially threaten the successful roll-out of microcredentials. Challenges range from concerns -- some justified, others less so -- about the quality of pedagogy to doubts about level, credit points, progression, coherence, assessment, certification, and labour market value. The paper assesses each challenge and identifies actions that could contribute to the successful roll-out of short courses and micro-credentials. These include a functioning national qualifications framework, transparent recognition procedures, internal and external quality assurance, reliable assessment, facilities for digital storage, funding for learners and providers, and stakeholder engagement. Lastly, success also requires the development of easily accessible digital registers of learners' achievements, micro-credential qualifications, short courses, providers, assessors, awarders, quality assurance agencies, credential evaluators, employers, and job and promotion opportunities. The paper draws on country experiences, studies, and projects from all world regions, and highlights good practices. It concludes with seven recommendations targeted at public policy-makers to foster coordinated action, including further research to better understand short-course provision at country level and obstacles to the development of micro-credentials, as well as their added value for individual learners, the economy, and society at large.