The acoustic treatment of an excessively reverberant civic coliseum is described. Before treatment the structure, originally an aircraft hangar, had a sharply peaked reverberation time of eight seconds in the region between 600 and 800 cycles per second. Thirty‐two thousand square feet of two‐inch‐thick Fiberglas panels were suspended in horizontal V's six feet below the parabolic metal ceiling. After treatment, the reverberation time is essentially uniform from 100 cps to 800 cps, with an average value of approximately 1.2 seconds. The method of construction and the mounting of the panels is described. Sound absorption coefficients for these panels are given, and a comparison made between the value obtained from the coliseum installation and the value obtained for 72 square feet of identical panel hung in the Defense Research Laboratory polycylindrical reverberation chamber.