Integrated light interrogation modules are provided. In embodiments, the subject integrated light interrogation modules include a flow cell having a light-accessible flow channel for transporting particles in a flow stream, a focusing optical assembly integrated with the flow cell, and a connector for operably attaching a fiber optic light conveyor to the focusing optical assembly, where the focusing optical assembly is projects excitation wavelength light from the fiber optic light conveyor onto a focal spot of the flow cell when the fiber optic light conveyor is operably attached to the connector. In certain embodiments, focusing optical assemblies also include a connector for operably attaching a fiber optic light collection element for collecting fluorescent light emitted by the particles transported through the flow cell. Flow cytometers, methods and kits for practicing the invention are also provided.