Response to N fertilizer in cotton is often unpredictable in the Southern High Plains, where water and heat units are the main constraints. The determination of in-season N needs could help avoid over fertilization. Remotely sensed reflectance indices have potential as tools for predicting in-season N needs. We tested this approach in an on-station, replicated N rate study (0 to 120 lb N/ac) in Lubbock and in an on-farm situation where the farmer applied a blanket application of 40 lb N/ac. The on-farm study consisted of half of an 120 ac center pivot field and soil samples were taken on 0.5 ac grid and analyzed for NO₃, P, and Zn. At both locations we took aerial infared photographs, hand-held spectral radiometer measurements and chlorophyll meter measurements at first square and at early bloom (Lubbock only). Both studies were hand-harvested and the on-farm study was additionally stripper harvested and yield monitored.