The kinetics of V+ + N2O and VO+ + N2O are studied using a selected-ion flow tube from 300-600 K at pressures of 0.25-0.70 Torr helium. V+ + N2O yields VO+ (k = 4.9 +/- 1.0 (T/300 K)(-03 +/- 0.2) x 10(-10) cm(3) s(-1)) in both ground and excited states. The secondary reaction VO+ + N2O -> VO2+ + N-2 proceeds near the collision rate at >10(-10) cm(3) s(-1), whereas thermalized VO+ + N2O studied as a primary reaction proceeds more than 100x more slowly (k = 4.2 +/- 1.0 (T/300 K)(-1.4 +/- 0.2) x 10(-12) cm(3) S-1). The results are best explained by contributions of competing pathways in V+ + N2O: a spin crossing to the lower energy (VO+)-V-3 in the exit well and a spin-conserved reaction yielding an electronically excited (VO+)-V-5. The intersystem crossing occurs in 35 +/- 20% and 37 +/- 15% of reactive interactions at 300 and 600 K, respectively. Statistical modeling of relevant reaction coordinates supports the lack of a temperature dependence, indicates an intersystem crossing rate constant of 10(11) s(-1), and yields derived bond and transition state energies.