This profile outlines the guiding principles and core competencies needed to build the capacity of practitioners and communities to effectively implement evidence in health and human services. Implementation support practitioners (ISP) are professionals who support organizations, leaders, and staff in their implementation of evidence-informed practices and policies. They identify, contextualize, and improve the use of evidenced-informed implementation strategies in a range of settings. They also build implementation capacity among teams, organizations, and systems. They can be referred to as coaches, improvement advisors, technical assistance providers, facilitators, consultants, mentors, and implementation specialists. Implementation support practitioners often reside outside of the service systems they work in, but may also reside within a service system when those systems have work units specifically designed to support implementation and scaling efforts. This ISP Profile presents "principles" that guide the work of ISPs and "core competencies" that they require to provide effective implementation support. Both were identified through an initial literature review, a document review, vetting with individuals providing implementation support, an integrative systematic review, and a content validation survey with international intermediary organizations. [This profile was prepared with the Centre for Effective Services and the European Implementation Collaborative. For "Implementation Support Practitioner Profile: Guiding Principles and Core Competencies for Implementation Practice, Version 3.0," see ED607181.]