The results of full-scale lateral load tests on 12 drilled piers are presented. The piers were 2 ft to 4 ft in diameter, 9 ft to 22 ft in length, and were constructed in hard, overconsolidated clayey soils. Both straight shaft and belled piers were tested and test loads of up to 600 kips were applied. Eight of the tests were conducted on level ground and four of the piers were tested on slopes ranging from 20? to 50—. Measured load-deflection data for piers on level ground are compared to computed results using existing procedures for obtaining p-y curves. Approximate procedures are proposed for analysis of piers of sloping ground. It is shown that with proper selection of soil-pile interaction parameters, reasonable predictions of load-deflection behavior of piers can be made.