Infragravity waves, motions with frequencies immediately below wind-generated sea and swell, are believed to be radiated seward from the surf zone, where they are excited by nonlinear interactions between waves in the sea-swell frequency band. We describe tidal modulation of sea surface elevation variance at infragravity frequencies observed in 8-30 m water depth, a few kilometers from shore at several California sites. Infragravity spectral levels vary by as much as a factor of 10 between high and low tide, possibly because the surf zone width and beach face slope vary significantly with tidal level on the usually concave-shaped beaches onshore of the observations. At a fixed sensor and with approximately constant sea-swell energy, the observed infragravity energy is lowest at low tide. ¿ American Geophysical Union 1995