Convective instabilities in shear flow are studied experimentally in a horizontal concurrent two-phase flow channel. The convective instabilities are generated by interphase mass transfer between the two immiscible liquid phases. Schlieren photography perpendicular to the interface is used to record both the disturbance shape and its orientation. Three separate convective modes are studied: A. surface tension driven, B. buoyancy driven, and C. coactive buoyancy and surface tension driven. The disturbance structure of mode A appears as rings which oscillate in diameter as they are swept downstream. Streamwise oriented roll vortices also appear when flow conditions move the interface into a region of higher shear. Modes B and C are both characterized by streamwise oriented roll vortices with mode C having an additional fine structure.