Investigations were performed utilizing a localized surface source of acoustic energy to generate disturbances in a laminar boundary layer flow to uncover the influence of induced surface vibrations on the stability of a shear flow boundary layer. Explorations were carried out over a frequency range of from 50 to 10,000 cps, using input sound pressure levels of up to 145 db re 0. 0002 dynes/sq cm. Results are presented which indicate the effect of sonic parameters (frequency, amplitude) on both the mean and fluctuating components of the boundary layer flow. Induced boundary layer oscillations are discussed, where appropriate, in terms of the stability theory of Tollmien and Schlichting. Studies of distortion of boundary layer oscillations are described and the role of such distortion in producing transition is discussed. Nonlinear secondary flows (streaming) generated by the localized source are also treated. Exploration of the influence of sonic excitation on premature transition produced both by increasing the free stream turbulence level and by use of a tripping wire is described.