Objectives of this study were to compare cow comfort and animal behavior (postural changes) as well as leg health and determine behavioral alterations in cows housed on sand or mattresses, and then switched to the alternate surface in a tie stall barn. During experiment 1 (new mattresses), there were significant differences in posture with cows on mattresses lying more than sand stalls. Two years later (Experiment 2), using a switchback design (animals were evaluated on one surface, then switched to the other), there were no differences in posture scores between mattresses and sand, and more variation was seen across weeks within surface type than across surface types indicating other factors affect cow posture in stalls. Animals housed on mattresses in both experiments had significantly higher hock scores (hock abrasions). When mattress animals were switched to sand, hock scores improved slowly. This work substantiates that either stall surface will work and be comfortable (especially compared to previous alternatives) but stall maintenance (sand quality, sand grooming, and especially adequate bedding on top of mattress top covers) is critical for stall comfort success.