D1.1 responds to the EU efforts to foster impact investment (an investment that delivers social, environmental and economic benefits) by developing an innovative RRI-based model for start-ups, complemented by an RRI-based impact investment indicator list in a multi-stakeholder (quadruple helix) context. This report, that provides the theoretical grounding for the entire project, represents a systematic review on socially responsible investment (SRI) by studying the extent to which current tools for achieving socially responsible investments are attuned to the specificities of social tech start-ups. To do this, the industry-standard screening method developed by GIIN, known as Impact Reporting and Investment Standards or ‘IRIS’, is employed as a case in point. This Responsible Impact Assessment Model culminates with 24 indicators enabling to ‘measure’ best practices for responsible start-ups or investors in start-ups, by checking strategies, drivers and barriers that these actors experience in their effort to engage in responsible investment in start-ups. Based on these insights, advice to start-ups on how to become more responsible organisations can be provided.