This guide describes the steps that national plant protection organizations (NPPOs) should follow when determining the status of a pest in an area, starting with identifying the pest and the area under consideration. It provides guidance on gathering and evaluating information, assessing sources of uncertainty, and how to use pest records and other relevant information to determine whether a pest is absent or present in the area and then to select the appropriate pest status category, as described in ISPM 8 (Determination of pest status in an area). This includes guidance on determining whether a pest is expected to establish in an area, and whether it is widely distributed or under official control. The guide describes the responsibilities of NPPOs when determining the status of pests within their territories, the requirements for national legislation to support actions relevant to pest status and how pest status determination fits within the international phytosanitary framework. It also describes how the outcomes of pest status determination may be used to support other key activities, such as preparing regulated pest lists, pest reporting, and securing or maintaining market access. Finally, the guide provides a number of case studies from around the world that highlight different aspects of the pest status determination process and how NPPOs deal with particular issues. By providing a deeper understanding of the process and the factors that should be considered when determining pest status, the guide aims to improve consistency in the processes used by NPPOs to make pest status determinations.