Stimulus control treatments for obesity are based on the unconformed assumptions that (a) instructions to alter eating behaviors produce change, and (b) that these changes in eating behavior cause weight loss. The behavioral changes produced by contingency contracting for weight loss are also unexplored. The present study used direct observation and self monitoring data to explore the functional relationship between (a) instructions in stimulus control procedures and behavior changes and subsequent weight loss, and between (b) contingency contracting and behavior changes and subsequent weight loss. The effect of the procedures was compared and their interaction also was examined. In an A-B-BC-B-BC design, four moderately obese adult females were individually treated for 25 weeks with alternating five-week phases of stimulus control or contingency contracting procedures. Instructions in stimulus control produced changes in all monitored eating behaviors while contingency contracting also produced improvements in some eating behaviors. The moderate weight losses produced by both procedures was associated with a reduction of snacking and eating rates. The results also show that therapist instructions are not necessary for behavior changes and that external contingencies are not needed for weight losses. Further development and application of direct observation procedures with a broader range of target behaviors are required to clarify the functional relationship between behavior change and weight loss.