This study investigated the effects of environmental consequences and data 'collection in a behavior contracting procedure for obesity. Also, a validity study examined the GSR as a subject-independent-monitoring technique. Sixteen subjects matched on sex and percent overweight were assigned to one of three contract conditions or to a no-treatment condition. The Data Only Contract Group received consequences for data collection. The With Consequences Contract Group received consequences for data collection and behaviors relevant to weight loss. The Without Consequences Contract Group received no consequences for data collection or behaviors relevant to weight loss. The With Consequences Contract Group lost significantly more weight ( p ≤ .05) than the No Treatment Group. Specific effects were not determined. The results of the validity study suggest that the GSR may not be a valid instrument as a subject-independent-monitoring technique. Factors affecting the galvanic skin response's- effectiveness were discussed.