Our objective was to develop a method to analyze reconstituted milk powders and estimate the composition (fat, protein. lactose, and solids) of the original milk powder using mid-infrared (MIR). Nonfat dry milk (NFDM) powders (about 10 g) were dissolved in 90 g of lab grade (LG) water at 40°C and held for 30 min. The reconstituted powders (14) were cooled in ice and then held overnight at 4°C for rehydration. The reconstituted powders were analyzed for solids by forced air oven drying, fat by ether extraction, protein by Kjeldahl on a TN basis, and anhydrous lactose by an enzymatic method. The reference chemistry results on the liquids were used to calculate the composition of the original milk powders. The MIR milk analyzer was calibrated to display the powder composition on weight of component per weight of powder directly from the MIR milk analyzer. Traditional MIR filter models used for routine milk analysis, not partial least squares (PLS) models were used. A goal was to simplify calibration, make the calibration more global across instruments, allow the use of standard liquid milk samples for calibration of MIR analyzers in different factories, and avoid the need for development and maintenance of PLS models as is normally done with near IR NFDM powder analysis. The mean reference chemistry composition of the NFDM powders was moisture (mean 3.71%, min 2.17% and max 6.33%), fat (mean 0.60%, min 0.52% and max 0.81%), TN protein (mean 35.63%, min 33.48% and max 37.02%), and anhydrous lactose (mean 49.49%, min 47.56% and max 50.66%). The standard deviation of the difference (SDD) and standard error of prediction (SEP) between reference chemistry and instrument on the powders were fat (0.020% SDD, 0.025% SEP on a mean of 3.71%), TN protein (0.11% SDD and 0.11 SEP on a mean of 35.63%), lactose (0.13% SDD and 0.13% SEP on a mean of 49.64%), and moisture (0.27% SDD and 0.26% SEP on a mean of 3.71%). In the future, we will attempt to develop a MIR method to directly measure undenatured whey protein for thermal history classification of milk powders.