We have determined, in the temperature range 227 K to 719 K, the absolute rate constant for the reaction O(<sup>1</sup>D)+N<sub>2</sub>O → products and, in the temperature range 248 K to 600 K, the fraction of the reaction that yields O(<sup>3</sup>P). Both the rate constants and product yields were determined using a recently-developed chemiluminescence technique for monitoring O(<sup>1</sup>D) that allows for higher precision determinations for both rate constants, and, particularly, O(<sup>3</sup>P) yields, than do other methods. We found the rate constant, <i>k</i><sub>R1</sub>, to be essentially independent of temperature between 400 K and 227 K, having a value of (1.37±0.09)×10<sup>−10</sup> cm<sup>3</sup> s<sup>−1</sup>. For temperatures greater than 450 K a marked decrease in value was observed, with a rate constant of only (0.94±0.11)×10<sup>−10</sup> cm<sup>3</sup> s<sup>−1</sup> at 719 K. The rate constants determined over the 227 K–400 K range show very low scatter and are significantly greater, by 20% at room temperature and by 15% at 227 K, than the current recommended values. The fraction of O(<sup>3</sup>P) produced in this reaction was determined to be 0.002±0.002 at 250 K rising steadily to 0.010±0.004 at 600 K, thus the channel producing O(<sup>3</sup>P) can be entirely neglected in atmospheric kinetic modeling calculations. A further result of this study is an expression of the relative quantum yields as a function of temperature for the chemiluminescence reactions (<i>k</i><sub>CL1</sub>) C<sub>2</sub>H+O(<sup>1</sup>D) → CH(A)+CO and (<i>k</i><sub>CL2</sub>) C<sub>2</sub>H+O(<sup>3</sup>P) → CH(A)+CO, both followed by CH(A) → CH(X)+hν, as <i>k</i><sub>CL1</sub>(T)/<i>k</i><sub>CL2</sub>(T)=(32.8<i>T</i>−3050)/(6.29<i>T</i>+398).