A general formulation for theY-junction semiconductor laser array is developed and analytic solutions are obtained for the important special case of identical waveguides. Modal thresholds, resonances, near-field, and far-field patterns are derived for the array modes. We show that the minimum threshold mode has identical modal intensities (except in the outermost waveguides) and the modal amplitudes are all in-phase. Thus the dominant mode radiates in a centered, narrow, single-lobe beam. Because the injected charges are utilized uniformly and efficiently, the mode is predicted to remain stable above threshold. All other array modes are shown to resonate at the same wavelength as the dominant mode, hut at increased thresholds.