A b initio self-consistent field (SCF) and correlated SCEP calculations have been used to study the relative energies and structures of cyanamide, isocyanamide, and the transition state for the rearrangement reaction. Isocyanamide is found to be 53 kcal less stable than cyanamide, larger than the typical isocyanide–cyanide energy difference. Correlation effects account for 11 kcal of this energy difference. Isocyanamide is found to be pyramidal with an inversion barrier of 6 kcal, larger than for cyanamide. The activation barrier for rearrangement of isocyanamide into cyanamide is about 46 kcal, which tends to support the prospects for the existence of isolated isocyanamide. Equilibrium rotational constants of isocyanamide and cyanamide for the optimized structures are presented.