A highly diluted, low-flame-temperature diesel engine combustion strategy with two separate fuel-injections per cycle was investigated using simultaneous optical diagnostics at a low-load operating condition. In-cylinder processes were visualized with a suite of laser/imaging diagnostics. The cool flame first-stage ignition reactions occur along the entire length of the jet for the first combustion event. For both injections, the second-stage ignition reactions occur after the end of injection, primarily in the downstream regions of the jet. OH is found throughout the cross-section of the jet, indicating greater mixing and leaner mixtures than observed for conventional diesel combustion. For the first combustion event, very little soot is formed and it is found in small pockets near the tip of the jet. For the second combustion event, much more soot is formed throughout the downstream jet cross-section. Finally, Sandia's conceptual model of diesel combustion has been extended to describe this operating condition.