The demand for six different foods was assessed using a concurrent available Fixed and Progressive Ratios for the Common Brushtail Possum. Responses to the left lever were reinforced with timed access to one food type on a FR 30, and responses to the right lever were reinforced according a geometric PR schedule with timed access to another food type. The food pairs were based on the results of single and paired stimulus preference assessments combinging pairs of mushroom, egg, foliage, blackberry, raw chicken, egg and locust. Cross-point demand functions showed the shift from the PR schedule to the constant FR 30 schedule occurred at about 30 responses for most food pairs. Cross-points that occurred before the equivalence point suggested a preference for food available on the FR schedule as the possum responded more for this food over responding on the PR schedule which initially required fewer responses. There was no significant difference in overall elasticity between the foods. This means that as the response requirement increased, responding decreased. Pooled consumption data from within each pair of foods showed inelastic demand for several preferred foods when paired with non-preferred foods. These data show that the context for assessing demand affects the conclusions of food preference.