The UN Guiding Principles on Business and Human Rights1have emerged as the global standard for companies’ management of their human rights impacts. Under the Guiding Principles, companies are expected to “know and show” that they do not infringe on human rights through their operations or business relationships. Human rights impact assessments represent a key first step in meeting this expectation. BSR has been conducting human rights due diligence with companies since our founding, a little more than 20 years ago. Over the past two years, we have worked with companies in multiple industries conducting human rights impact assessments (HRIAs) that align with the Guiding Principles (GPs). This report is intended to capture the lessons we have learnedand to share our eight guidelines for conducting effective HRIAs, as well as step-by-step guidance on the four levels of HRIAs: corporate, country, site, and product.