To ensure that a laboratory produces credible analytical results, it is important to participate in collaborative studies utilizing check samples as a method of implementing a quality control procedure. This paper describes the following twelve check sample programs in which the Canadian Forest Service has participated during a 25‐year period to ensure that it produces high quality analytical results: Acid Rain Direct/ Delayed Response Project, Alberta Institute of Pedology, AOAC INTERNATIONAL, Canada Soil Survey Committee, Energy Resources Conservation Board, Expert Committee on Soil Survey, International Soil‐analytical Exchange, International Union of Forestry Research Organizations, Laboratory Exchange, Long Range Transport of Air Pollutants, Utah State University, and Western Enviro‐Agricultural Laboratory Association.