The purpose of this document is to provide guidance on the assessment of cumulative risks and impacts in the Great Barrier Reef (GBR). The guidance is intended to be applied at a regional or plan of management level, and at a development application level. The guidance details the necessary concepts and outlines a series of steps to work through and link multiple pressures with their impacts on identified values. It is not meant to replace existing frameworks and guidance for standard environmental risk assessments, rather it is intended as a supplement to these approaches that facilitates the understanding and assessment of cumulative impacts in complex ecosystems of the GBR. For each step, this guidance provides criteria to select the appropriate tools or methods to use in cumulative impact analysis. The tools and methods identified will provide robust assessments and will reduce the uncertainty at each step. While a full and rigorous environmental risk assessment can take various forms and have many steps, this guidance is specifically designed to address analysis of cumulative impacts within a standard risk assessment framework. Beyond the guidance provided in this work, we anticipate the need for a “tool-box”, largely internet based, to provide access to existing and developing resources and approached for completing the more technically challenges steps of the risk assessment. This report (Part 1) describes the steps in the guidelines and their application. Part 2 will describe a detailed case study from the GBRMPA region and a plain language summary that can be used by proponents and regulators as an entry point to the technical guidelines contain summaries, specific to GBRMPA, QLD State Government and DAWE.