Laser flash photolysis of ethyldiazoacetate (351 nm, 17 ns) generates carboethoxycarbene, which can be intercepted with either pyridine or acetone to produce a UV-vis active ylide. Analysis of the yield of ylide as a function of either pyridine or acetone concentration leads to estimates of the carbene lifetime. Absolute rate constants of reaction of carboethoxycarbene with alcohols, sulfides, ethers, and alkenes were deduced.