This thesis is an investigation of the effects of gel mat stall flooring on the activity, lying behavior and stall preferences of dairy cattle. In the first study, lactating cows (n=24) were housed in tie stalls on four flooring surfaces for one week each, in a cross-over design. Observations showed that housing cows on gel mats increased total lying time and decreased the time required to transition between lying and standing. The same cows housed on the foam mats and rubber mattresses spent longer standing. In the second study, non-lactating cows (n=18) in a free stall environment spent more time lying, and had a shorter latency to lie down after entering the gel mat stall. Cows restricted to the foam mat spent the most amount of time standing. Cows did not show a particular preference for either stall flooring surface during the final choice phase of the experiment. Results from both studies indicate that housing cows on gel mats promotes lying behavior.