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Investigations concerning microwave techniques for remote estimation of soil moisture have shown Increased interest in the study of vegetation effects on the estimates of soil moisture. This paper addresses only combinations of passive microwave and visible/infrared systems. An approach is presented whereby visible/near infrared data are used to develop corrections in the microwave soil moisture signal to account for vegetation effects. Microwave brightness temperature measurements at near nadir took angles were made with 1.4- and 5-GHz systems. Visible/infrared data were collected with the NASA NS001 Thematic Mapper Simulator and the M2S imager at the time of the microwave observations. The visible/infrared data were used to calculate Perpendicular Vegetation Index (PVI) which was then related to the change in sensitivity of the microwave measurement to surface soil moisture. It was found that effective estimation of soil moisture in the presence of vegetation can be made with L-band microwave radiometers and visible/infrared sensors when the PVI is less than 4.3. If implemented from a space platform, this technique can provide a pragmatic means of estimating moisture over many agricultural areas without the expensive necessity of collecting ground data.