The ongoing development and adoption of decision support tools within the Australian cotton industry has led to the need for refinement of several crop data collection techniques. Present and future applications of the crop growth simulation model OZCOT (Hearn, 1994), whole farm water use efficiency calculator (Tennalcoon and Milroy, 2000), and the crop water management tool HydroLOGIC will be greatly enhanced by updates of crop status and development entered throughout the season. One of those needed is crop leaf area, which will help to improve estimates of evapotranspiration of moisture from the soil and crop. Leaf area of the crop is often referred to as the leaf area index (LAI), which represents the leaf area of the crop above a known area of ground surface. This paper presents the results of initial studies comparing a range of simple methodologies that could be used by cotton managers to obtain estimates of Lal throughout the cotton season