Standardized techniques for monitoring and evaluating (M&E) changes in indoor air quality and stove fuel performance were developed and deployed in two NGO-led programs to disseminate improved cookstoves (ICSs) in India and one in Mexico. This paper describes the objectives and characteristics of these monitoring and evaluation methods and how they were deployed. The results showed major and mostly statistically significant improvements in 48-hour indoor air pollution concentrations in those households using the stoves one year after introduction. Kitchen levels of carbon monoxide reduced 30-70 % and concentrations of small particles reduced 25-65 %. Results for stove performance were mixed, with some stoves achieving improvement in one or another of the short-term metrics that are part of the water boiling test (WBT) used to evaluate stoves in laboratory (controlled) settings. The kitchen performance test, which measures fuel use in households under actual use, was less easily conducted because of high variation and difficult field logistics. The results are more promising, however, with statistically significant reductions in fuel use per person ranging from about 20 to 67 %. From the results, it also seems clear that several indicators of stove performance derived from the WBT are not good predictors of actual fuel use and thus should be confined to evaluations during the design stage of stove development. In two of the sites, the reductions in pollution roughly matched those in fuel use, although in the third, indoor air pollution may have reduced a bit more. This indicates perhaps that for all the monitored stoves, much or all of the benefits of each type came from improving the heat transfer into the pots and not from either increased combustion efficiency of the fires or stove-venting