Ephrussi-Taylor, Harriett (Western Reserve University, Cleveland, Ohio), and Barbara A. Freed. J. Bacteriol. 87:1211–1215. 1964.—Pneumococcal cultures, in which competence to transform develops in an acute, synchronous fashion toward the end of growth of the cultures, show an arrest in lysine incorporation into trichloroacetic acid-insoluble residues during the competent period. Thymidine incorporation into deoxyribonucleic acid is momentarily halted after the development of maximal competence. It is suggested that competence is associated with a brief arrest of normal cell-wall synthesis.