Solubilities and vapor pressures from the literature are combined with calculated octanol/water partition coefficients, K (sub ow), to assess the expected environmental behavior of about 50 dyes. The solubility suggests the potential for a 30- to 150-fold concentration enhancement in sediments and bioconcentration of about 1,000 times in the absence of metabolism. The data also indicate that solubilities computed from K (sub ow) for disperse dyes is 10 to 100 times smaller than reported for most other compounds. Henry's Law constants calculated from solubility and vapor pressure show that the disperse and vat dyes will be entirely gas-phase-controlled in their rate of volatilization from water and that the process will be extremely slow. No definitive conclusions can be drawn about the behavior of more recently developed disperse dyes. The available physical constants are compiled along with structures, Color Index numbers, CAS numbers, and names for 80 compounds.