Crop yields are primarily light-limited under shade. This study was conducted to determine the effect of shade intensity and duration on growth, development and grain yield of corn (Suwan 1 Cycle 11). The experiment was conducted at the National Corn and Sorghum Research Center, Nakhon Ratchasima province, from May-September, 1991. A randomized complete block design with four replications was utilized. Treatments consisted of all combinations of a 2x2 factorial with two shade intensities (65% and 80%) and two durations of shade application (all season and at flowering stage) as well as a check treatment. All season shading delayed tasseling more than did shade at flowering stage only. Increasing shade intensity from 65% to 80% caused a dramatic delay in silking. These resulted in an increase in tasseling-silking interval for all shade treatments relative to control. Plants shaded all season at both shade levels showed a tendency for Leaf Area Index (LAI) reduction. Stalk diameter also showed a decreasing trend when shade was applied all season. It is believed that the increase in plant height due to shade would consequently reduce stalk diameter. Plant dry weitht from shading at both stages kept increasing even at week 14 after planting. However, shaded plants produced less dry weight than control. Shading had no effect on 1000-seed weight but caused a reduction in numbers of ear per plant and ear weight especially when shaded at flowering stage. All season shading not only reduced plant stand but also increased lodging percentage. Shading produced less grain yield than the control with a pronounced effect when 80% light reduction was applied. The experiment did suggest that corn is one of potential field crops to be grown in agroforestry system or between rows of horticultural crops.