The photodissociation spectroscopy and dynamics of the HNCN free radical have been investigated by fast beam photofragment translational spectroscopy. Predissociative transitions for both the (B) over tilde (2)A'<--<(X)over tilde> (2)A " band and a higher-energy band system assigned to the (C) over tilde (2)A "<--<(X)over tilde> (2)A " band were observed. Photofragment mass distributions indicate that N-2 loss is the primary dissociation pathway. Translational energy distributions reveal a resolved vibrational structure of the N-2 fragment, suggesting that the HNCN radical first isomerizes to a cyclic HCN2 intermediate. A dissociation mechanism is proposed in which electronically excited HNCN undergoes internal conversion to the ground state, followed by isomerization to cyclic HCN2 and dissociation through a tight three-center transition state. The HNCN bond dissociation energy D-0 and heat of formation Delta H-f(0)(HNCN) were determined to be 2.80 +/-0.03 eV and 3.35 +/-0.03 eV, respectively.