A theoretical examination of a number of factors affecting the behaviour of drilled piers in soft rock is presented. Firstly, the fundamental difference between tests commonly used for determining the peak average side shear resistance along a socketed pier is discussed. Secondly, the effect of interface strength parameters, dilatancy, and the relative Young's modulus of the pier and rock upon the average mobilized side shear resistance is examined. Thirdly, a series of theoretical solutions are presented in the form of design charts to provide a simple means of estimating the load—deflection response of piers both before and after full slip has developed along the pier shaft. Finally, the effect of weak horizontal seams adjacent to the pier is considered.Key words: drilled shafts, piers, piles, rock, theory, settlement, displacement, analysis.