Greenhouses are essentially large solar collectors. Without any cooling, in warm regions, internal air temperature can quickly reach lethal levels during summer. With inadequate cooling, excessive temperatures can significantly reduce yield and quality. Hence, cooling is essential for proper greenhouse operation. An overview of the good agricultural practices for greenhouse cooling is presented and discussed. Among the methods presented are manipulations in the common types of cover material, shading, whitewashing, natural and forced ventilation, evaporative cooling, use of heat exchangers and phase change materials. Advantages and drawbacks of the different methods are presented and discussed.