The in-line moisture meter at the planer measures the moisture content of every board. This information is often not used for process improvement because of difficulty in linking the moisture information to a point in the process and reliable statistical methods for analyzing the data. Test programs in which the moisture contents measured at the planer were used to create process charts for kilns and to identify kilns or zones within kilns with high moisture content or moisture content variability were established in four mills. Tagging units, either with bar codes or with alphanumeric tags, to identify their location in a kiln was a practical and effective way to diagnose kiln performance when the moisture content information collected at the planer was associated with location. Wet areas and dry areas could be identified, and the consistency of moisture content from charge to charge could be evaluated, as could the variability within charges. The latter items can be accomplished without knowing the location of a unit in the kiln if the kiln from which the lumber came is known at the time of planing. The methods developed also allow other factors, such as operator decisions and the performance of in-kiln moisture meters, to be evaluated.