Listeria monocytogenes grew between 3 and 45C. Growth at 10C was at a rate characteristic of psychrophilic bacteria. The increase in the duration of the lag phase of growth with decreasing temperatures was expressed with a hyperbolic curve which indicated an infinite lag time at 3.3C. If this relationship between lag time and temperature is a general phenomenon, it would provide a relatively rapid method for estimating minimal temperatures of growth. Initial rates for oxygen consumption during glucose metabolism and for uptake of the nonmetabolized sugar, 2-deoxyglucose, had temperature coefficients (10–30C) of about 1.5. Growth at 10C increased the rate and the capacity of 2-deoxyglucose uptake by exponential-phase cells. Uptake and incorporation of L-leucine was relatively rapid at 10C but the temperature coefficients were greater than 2. High temperature coefficients (greater than 2.5) for nicotinamide adenine dinucleotide oxidase and lactic dehydrogenase activity in cell-free preparations indicated that the psychrotrophic properties of L. monocytogenes depend on the structural integrity of the cell. We suggest that the cold-resistant sugar-transport system stimulates metabolism at low temperatures by providing high concentrations of intracellular substrates.