The ASCE DEI Best Practices Resource Guide is a collaborative effort by the MOSAIC committee, aimed at promoting diversity, equity, and inclusion (DEI) within the civil engineering profession. The guide acknowledges the contributions of various individuals and organizations in its development, emphasizing the importance of diverse perspectives in engineering solutions that serve society. It outlines ASCE's commitment to DEI, which has evolved over the years, culminating in the establishment of MOSAIC as a leadership body focused on advancing DEI initiatives. The guide provides strategies across five key areas: Events, Leadership and Engagement, Strategic Partnerships, Assessment, Accountability and Training, and Communication, to ensure that ASCE activities are inclusive and accessible to all.%0aThe text outlines the ASCE Diversity, Equity, and Inclusion (DEI) Best Practices Resource Guide, which aims to promote equitable opportunities within ASCE's various divisions. It includes sections on fostering engagement, forming strategic partnerships, assessing and training for DEI initiatives, and ensuring inclusive communication. The guide was developed through collaboration among task teams, which identified existing resources, refined content, and incorporated feedback from reviewers. It is intended to be a living document that will be periodically updated to reflect ongoing developments in DEI discourse and research.