Pure cultures of yeast, molds, and bacteria were screened for neutral pH optimum β-galactosidases (lactases) that would be suitable in dairy products applications. Only 2 of 125 identified and 10 of 250 unidentified cultures warranted further study. These cultures produced high levels of β-galactosidase with moderate galactose product inhibition. Characterization of the partially purified enzymes from unidentified cultures revealed that all required either Na+, K+ or Mg++ cation activation, were inhibited by Cu+ +, Mn+ +, and Fe+ + +, were most active around pH 6.8, and were unstable during storage (at either – 196 C or 4 C) except in the presence of 0.5 m ammonium sulfate. Most of the enzymes compared favorably in performance with a commercially available β-galactosidase when tested in skim milk.