The wide range of sampling and analysis protocols used for documenting biodiversity and assessing ecological and waterbody conditions often limits or completely deters widescale and meaningful summaries. Where protocols exist, objective information on the quality of data supporting such summaries can be inadequate, thus reducing confidence with which assessments can be aggregated at regional, continental, and global scales. While some regions, such as the European Union and the United States, have harmonized their protocols, most countries and regions have not done so. Many of these same regions and countries do not have nationally accepted protocols in place for the monitoring and ecological assessment of freshwater habitats. We envision the harmonization of biodiversity and biological monitoring and assessment to be at least a three-phase endeavour. Initially, there needs to be agreement on indicators and the supporting sampling and analysis protocols. Second, explicit and direct data quality and performance standards and adequate quality control procedures will be implemented, and the results made widely available. Third, datasets are merged, remaining inconsistencies resolved, and indicators reported. To help close the gaps in knowledge and application, the IUCN Species Survival Commission (SSC) Task Force on Global Freshwater Macroinvertebrate Sampling Protocols (GLOSAM) was established in 2021. This endeavour was undertaken accepting that some regions and countries will have limited capacity and administrative support for broadscale development of monitoring and assessment programs. The GLOSAM Task Force aims to: (a) support the application of biodiversity and bioassessment protocols based on benthic freshwater macroinvertebrates, (b) establish globally accepted, harmonized steps for sample collection and data treatment, both for bioassessment and species inventories, which also account for specific biogeographic requirements, (c) ensure the collection of ecologically relevant data of known and acceptable quality and (d) support, promote, and facilitate regionally comparable bioassessment schemes.