Seals-of-approval have been employed as one of the information sources at the time of purchase. However, little is known about how seals’ sponsoring organizations affect consumers’ decision making and how consumers use seals in different food categories such as healthy-seeming vs. unhealthy-seeming products. Applying Consumers’ Decision Making Model and Signaling Theory to the above inquiry, I propose that people who are exposed to healthy-seeming food products are using seals-of-approval to evaluate brand quality and credible third-party seals may significantly affect their brand attitude and buying decision. In contrast, the seals-of-approval on unhealthy-seeming food products may not affect significantly consumers’ brand attitude or buying intention because consumers rely more on their previous experience such as taste when choosing unhealthy foods. After this theoretical proposition, next step will be an experimental survey to test suggested hypotheses.