Smaller, more targeted, and more flexible than traditional education and training programmes, micro-credentials have become a prominent feature of education, training and labour market policy discussions in recent years. Several OECD countries have already started the development of national micro-credential ecosystems, and many others are looking to follow suit. This OECD Education Policy Perspective serves as Part A in a two-part series of summary papers. This paper examines the evolving landscape of micro-credentials, focusing on the development of public policies that can foster effective utilisation of micro-credentials for lifelong learning, upskilling and reskilling. The paper also provides a self-assessment tool for micro-credential policy implementation, which identifies a range of policy measures and considerations needed for the establishment and effective operation of national micro-credential ecosystems. This document was authored by Shizuka Kato from the OECD Higher Education Policy Team and Thomas Weko from George Washington University.