Rationale Bulk and position‐specific stable isotope characterization of nitrous oxide represents one of the most powerful tools for identifying its environmental sources and sinks. Constraining 14N15N18O and 15N14N18O will add two new dimensions to our ability to uniquely fingerprint N2O sources. Methods We describe a technique to measure six singly and doubly substituted isotopic variants of N2O, constraining the values of δ15N, δ18O, ∆17O, 15N site preference, and the clumped isotopomers 14N15N18O and 15N14N18O. The technique uses a Thermo MAT 253 Ultra, a high‐resolution multi‐collector gas source isotope ratio mass spectrometer. It requires 8–10 hours per sample and ~10 micromoles or more of pure N2O. Results We demonstrate the precision and accuracy of these measurements by analyzing N2O brought to equilibrium in its position‐specific and clumped isotopic composition by heating in the presence of a catalyst. Finally, an illustrative analysis of biogenic N2O from a denitrifying bacterium suggests that its clumped isotopic composition is controlled by kinetic isotope effects in N2O production. Conclusions We developed a method for measuring six isotopic variants of N2O and tested it with analyses of biogenic N2O. The added isotopic constraints provided by these measurements will enhance our ability to apportion N2O sources.