Ten overtone and combination-bands of iso-dicyanoacetylene (NC3NC), produced by in situ pulsed ultraviolet laser. photoisomerization of dicyanoacetylene in an argon matrix, have been assigned in our Fourier-transform absorption-spectra. Experimental band frequencies, relative band intensities, and derived anharmonicity constants are compared in detail to CEPA-1 theoretical calculations. The agreement here, even for overtone band intensities, is excellent.