The Stratosphere-Troposphere Analyses of Regional Transport (START08) studied the chemical and transport characteristics of the extratropical upper tropospheric and lower stratospheric (ExUTLS) region using the NSF/NCAR HIAPER aircraft. In the ExUTLS, multi-scale dynamics, coupled with chemistry, controls and redistributes a suite of radiatively important trace species, including ozone, water vapor, and CO2 in addition to aerosols and particles. The primary objective was to characterize the contribution of transport to the chemical-microphysical structure of the ExUTLS region. START08 had a joint payload and flight operation with the Pre-HIPPO experiment.