Microchannel heat sinks are widely regarded as being among the most effective heat removal techniques from space-constrained electronic devices. However, the fluid flow and heat transfer in microchannels is not fully understood. The pumping requirements for flow through microchannels are also very high, and none of the micropumps in the literature is truly suitable for this application. Results are reported from a wide-ranging research program being conducted on microchannel heat sinks and micropumps to understand fluid flow and heat transfer in microchannels and to identify pumping requirements and suitable mechanisms for pumping in microchannels. In particular, experiments have been performed to show that conventional correlations for fluid flow and heat transfer adequately predict the behavior in microchannels of hydraulic diameters as small as 250 mum. Pumping requirements of microchannel heat sinks have been analyzed, and the size of the microchannels have been optimized for minimum pumping requirements. Results are also provided from a comprehensive review of micropumping technologies in the literature.