Accurate and efficient phenotyping is currently the biggest hurdle for evaluating large populations in plant breeding and genetics.  To address this bottleneck a novel, handheld phenotyping platform was developed and used to determine the performance of 10 historical and current elite wheat (Triticum aestivium) breeding lines at the International Maize and Wheat Improvement Center (CIMMYT).  The lines were planted under heat stress during the 2013 growing cycle at Ciudad Obregon, Mexico, and evaluated multiple times throughout the growing season.  A handheld, high-throughput phenotyping platform was developed by integrating a GreenSeeker sensor, an infrared thermometer (IRT), and a GPS antennae for geo-referenced data collection.  The “Phenocorn” enabled simultaneous collection of normalized difference vegetative index (NDVI) and canopy temperature with precise assignment of all measurements to plot location with the GPS.  The correlations among traits measured and yield as well as precision of the measurements against currently used sensors was examined to determine the utility of the Phenocorn.