The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene, 1CH2 (ã 1A1), with various oxygen-containing organic species. Removal rate constants for some 27 alcohols, ethers, ketones, aldehydes, carboxylic acids, and esters are reported for the first time. The removal rate constants for H2O and CH3OH have been remeasured and found to be in excellent agreement with values determined by other researchers. Improved removal rate constants for C2H5OH, n-C3H7OH, CH3OCH3, CH3CHO, CH3COCH3, CH3COOH, HCOOCH3, and CH3OCOOCH3 are also presented. In all cases the removal rate constants are large, indicating that reaction is the dominant process leading to loss of 1CH2. Comparisons are drawn between the reactivities of the various functional groups and between them and their hydrocarbon analogues. Because of the large data base provided by these measurements, mechanistic information can be inferred in a number of instances.