The objective of this publication is to provide guidance to WMO Members on how to develop and implement a quality management system (QMS). The Guide details the steps required to obtain certification of compliance with the ISO standard ISO 9001:2015, Quality Management System – Requirements (ISO, 2015c)It also provides the steps for transition from ISO standard ISO 9001:2008 (ISO, 2008) to standard ISO 9001:2015 (ISO, 2015c). It is especially focused on WMO Member National Meteorological and Hydrological Services (NMHSs). However, it could be successfully utilized by other service providers, such as non-NMHS aeronautical meteorological service providers, to help them meet the ICAO Annex 3 quality assurance requirements. It is also applicable to the management of relevant WMO programmes by WMO constituent bodies.