We discuss recent advances in the field of optoelectronic device integration. Several problems and advantages associated with integration are illustrated by discussing in detail three device types which are currently undergoing intensive investigation: integated laser transmitters, integrated p-i-n photodetector receivers, and arrays of individually addressable detectors and light emitters. Devices fabricated using either GaAS or InP-based material systems with application at wavelength of 0.82-0.87 µm and 1.3-1.55µm, respectively, are considered. It is concluded that the pursuit of optoelectronic integration will lead to an increase in device functionality, an improvement in performance, and a reduction in cost of the integrated device as compared with its hybrid counterpart.