The S-1 vibronic spectrum of acrolein (CH2CHCHO) was obtained in a supersonic free-jet expansion using cavity ringdown spectroscopy. Comparison of room temperature and free-jet spectra was used to assign vibronic transitions. Computations using the configuration interaction-singles method were used to predict the values of the S-1 fundamental vibrational frequencies. The current set of assignments increases the number of identified bands from 27 to 59, corrects 16 misassignments in the previous literature, and identifies two new fundamental bands. A lower limit for the lifetime of the S-1 vibronic origin was determined from linewidth measurements to be 1.8-2.1 ps.