To estimate response of pile groups under lateral loading, a widely accepted approach is to use the curve of soil resistance, p versus local pile deflection, y (p-y curve). As the response is dominated by the limiting force per unit length pu, various expressions have been developed for evaluating pu. Given a generic pu profile, response of a laterally loaded pile or group can be readily predicted using a spreadsheet program called GASLGROUP, which in turn is based on closed-form solutions for a single pile (Both the solutions and program were developed by the author). In light of 70 field tests on single piles and 30 tests on pile groups, an extensive back-estimation carried out recently indicates that only three parameters along with p-multipliers are sufficient to accurately predict the response of laterally loaded single piles and pile groups. In this paper, pu profiles are deduced against measured response of a single pile and two typical pile groups under static and cyclic loading. The shadowing effect (p-multipliers), and the effect of the pu profile, and loading properties (static or cyclic) on piles in groups are examined. Typical calculations are presented in figures and tables.