Abstract: Nonlinear optics has produced a wealth of spectacular scientific results, opening new fields such as harmonic generation, parametric amplification and oscillation, optical solitons, phase-conjugation, stimulated Raman scattering. Since the early days, it was clear that third-order nonlinear optical phenomena had the potentiality for the implementation of all-optical integrated devices for applications related to information and communication technology, but the accomplishment of such a program was made difficult by the lack of appropriate materials and realization schemes. The new trend emerging in the last few years is based on the utilization of cascaded interactions in second-order materials. The consideration that cascaded effects can give rise to large effective third-order nonlinearities with ultrafast response times and perfect transparency of the nonlinear medium, associated with important technological advances in the fabrication of microstructured waveguides, has triggered an enormous interest in both academic and industrial laboratories. In particular, it has been shown that the technique of optical frequency conversion, with the associated spectral inversion, can have important applications in optical communication networks based on wavelength-division multiplexing. The results described in this article, all of very recent publication, show that significant steps have been made in the direction of understanding nonlinear optical interactions in a confined geometry and of developing integrated optical devices.