The rationale for civil society organisations (CSOs) to engage in multistakeholder initiatives is to influence corporate activities to move in a more sustainable direction. Over the past 15 years, CSOs, which include non-governmental organisations (NGOs) and trade unions, have been involved in many different initiatives involving multiple stakeholders. This guidebook takes stock of the experiences they have gained and identifies lessons they have learned in the process. The aim is to strengthen the influence of CSOs in multi-stakeholder initiatives (MSIs).