This chapter critically reviews and evaluates a pioneering and highly collaborative cross-sectoral approach to sustainably embedding best practice in relation to gender identity and expression in Irish Higher Education Institutions (HEIs). We introduce the concept of gender identity and expression and examine the background and context to this work in Irish HEIs. In particular, we describe and evaluate an innovative collaborative project, ‘The development and implementation of a Gender Identity, Expression & Diversity Training Programme for staff in Irish HEIs’, funded under the Higher Education Authority’s 2020 Gender Equality Enhancement Fund (GEEF) which aimed to embed inclusive gender identity, expression and diversity training and best practice into Irish HEIs. The two-phase project began in 2020 and aimed to combat stereotyping and unconscious bias in relation to gender identity minority groups, and to invoke inclusion for the LGBTQ+ community in the wider sense. It also aimed to benefit other HEIs by developing and sharing resources and best practice in this area. This paper presents the outcomes, challenges and learnings from this unique project, providing a critical reflection on work in this area. It also reflects on opportunities the project presented the partners, which acted as a catalyst for further inclusive gender equality work. We conclude with sustainable recommendations for other HEIs to ensure greater inclusion and equality for the gender diverse community across HE and beyond.