Investigation of a two-phase, horizontal, stratified, flow regime is being performed with pulsed laser velocimetry to determine the interface drag force due to the relative motion between the two fluids at the interface. This technique is a full-field, two-dimensional, noninvasive flow visualization technique. The main advantage of PLV techniques is that simultaneous qualitative and quantitative full-field maps are produced of fluid flow parameters (such as velocity and shear stress) over extended areas. PLV data is acquired by shaping a pulsed laser beam into a thin sheet of light, and passing this sheet of light into seeded fluid. The light scattered from the reflective tracer particles is then imaged with a digital camera. By synchronizing camera frame acquisition with the laser pulse frequency, a time sequence of the fluid motion can be captured. The data is analyzed with imaging system hardware and a series of new image processing and tracking analysis software developed for flow experiments.