Infragravity waves (20<T<300 sec) have been implicated as playing important roles in the nearshore zone, although their occurrence in tidal inlets is poorly documented. Field measurements of long period waves in Shinnecock Inlet, New York, are presented from observations of surface displacement obtained with a system of wave-gauging manometer tubes and a pressure sensor, and near-bottom current velocity obtained with an electromagnetic current meter. Time series contained small-amplitude infragravity motions as well as longer period (T≥1000 sec) oscillations. Infragravity band motion contributed as much as 34% of along-channel and 28% of cross-channel velocity variance, although the wind-wave band entirely dominated surface displacement variance. Peak infragravity variance was occasionally associated with forced or resonant wave modes in the inlet. It is suggested that long waves superimposed on strong tidal flow may enhance mean current shear stresses sufficiently to augment tidal inlet sediment transport.