This article is devoted to integrated acousto-optic devices and applications with emphasis on the basic planar guided-wave acousto-optic (AO) Bragg diffraction geometry, Bragg cell modulators, the basic collinear AO mode converters, and the resulting integrated optic modules for radio frequency (RF) signal processing and optical wavelength filtering. In Section 2, the interaction geometry, physical mechanism, analytical treatment, the key device parameters of a basic planar AO Bragg cell modulator, and viable substrate materials are presented. The techniques for realization of efficient and wideband planar AO Bragg modulator and deflector, using multiple tilted surface acoustic waves (SAWs) and phased-array SAWs, and applications to multiport optical switching are also presented. Subsequently, the architecture for a monolithic integrated AO RF spectrum analyzer and that for hybrid counterparts in planar and spherical waveguide LiNbO₃ substrates, and the fabrication technologies involved are presented in Section 3. Prospects for further advances toward monolithic integration for the integrated optic RF spectrum analyzers are also briefly mentioned. The other major application of integrated acousto-optics for tunable optical filtering using collinear mode conversion is treated in Section 4.