We have identified a sample of cool field brown dwarf candidates using IRAC data from the Spitzer Deep, Wide-Field Survey (SDWFS). The candidates were selected from 400,000 SDWFS sources with [4.5] = 1.5 and [4.5] - [8.0] 70 pc. The reddest brown dwarf candidate (SDWFS J143356.62+351849.2) has [3.6] - [4.5] = 2.24 and H - [4.5] > 5.7, redder than any published brown dwarf in these colors, and may be the first example of the elusive Y-dwarf spectral class. Models from Burrows et al. predict that larger numbers of cool brown dwarfs should be found for a Chabrier mass function. Suppressing the model [4.5] flux by a factor of 2, as indicated by previous work, brings the Burrows models and observations into reasonable agreement. The recently launched Wide-field Infrared Survey Explorer will probe a volume similar to 40x larger and should find hundreds of brown dwarfs cooler than T7.