A large acceptance sampling calorimeter with wavelength shifter readout for studying high p^ hadronic interactions has been assembled at Fermilab. The calorimeter consists of a 132 segment tower structure of S-8.5 radiation lengths of lead followed by 6-8 absorption lengths of iron. A procedure to balance the responses of all 528 calorimeter modules using muons steered by a computer controlled rotating dipole is described. Results on the resolution, linearity, and uniformity of the calorimeter obtained with electrons and hadrons in the momentum range 1-13 GeV/c are presented. For iron sampling thicknesses of 1.3cm, 1.9cm, and 2.8cm the hadron energy resolution is found to be .76, .82, .91/E respectively, while the electron energy resolution obtained is .27, .35, and .37/E.