The absorption characteristics of commercial CdS-containing yellow glass which shows constant transmitted intensity over a range of incident CW laser intensity have been studied at room temperature. Although the thick specimen (t>0.6 mm) shows only a broad step-like feature near λ>460 nm, a thin (t-0.09 mm) specimen shows two absorption features which can be interpreted as the first two quantum-confined exciton absorption features corresponding to a crystallite size of -45 Å. The absorption spectrum of a sample (t∼O.6 mm) heated for 15 min. at 700°C shows two new absorption features at 450 nm and 380 nm, which correspond to a much smaller crystallite size of -25 Å. This reduction in size is not inconsistent with estimates made from a well-known model for crystallite growth. Some consequences of these changes in the absorption features on the optical nonlinearities of the glass will be discussed.