Phase-matching nonlinear interactions by periodic variations in the nonlinear susceptibility, quasi-phase-matching, offers advantages in accessible tuning range and in choice of nonlinear coefficients over the conventional birefringent technique. Periodically reversed ferroelectric domains can be used to create monolithic structures with the necessary high-spatial-frequency variations in the nonlinear susceptibility. We present two techniques for the fabrication of periodically-poled lithium niobate crystals, and results for bulk and guided-wave second harmonic generation of blue and green light.