Since the 1990s, there has been a growing corpus of evidence on Lesbian, Gay, Bisexual, Trans, Intersex and other Sexual and Gender Minority (LGBTI+) youth. However, most of these studies were conducted in the North America, and it remains unclear whether their findings can be generalised to other countries and cultures. The third goal of the Irish LGBTI+ National Youth Strategy 2018-2020 was to develop the research and data environment to better understand the lives of LGBTI+ young people. This study aimed to draw the landscape of existing research on LGBTI+ youth in Ireland and other European countries, and identify research and data gaps that need to be addressed. Method: Using a scoping review technique, we employed a multi-method search to identify research outputs and databases on LGBTI+ young people in peer-reviewed and grey literature. Identified outputs were screened against pre-set inclusion criteria, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines; then, several types of information were extracted from studies meeting inclusion criteria. We used standardised methods to evaluate the quality of each outputs. Finally, research and data gaps were identified. Results: 4,603 records were found. Following screening, 126 outputs were entered to the analysis. The studies and databases varied largely in method and quality. Important evidence gaps were found on the health and needs of transgender and intersex youth; the sexual health of LGBTI+ youth; and their employment and career opportunities. The predominant ‘victim’ narrative in the vast majority of existing studies need to be balanced with investigating positive predictors of well-being and evidence-based good practice for improving LGBTI+ youth lives. Conclusion: Some areas of LGBTI+ youth lives have a thin or practically non-existent evidence base. Identified research and data gaps need to be addressed by methodologically sound studies.