Baked sediments beneath lava flows on the Snake River Plain, Idaho, with independent age control by either 14C or K/Ar dating were analyzed to evaluate the accuracy of the thermoluminescence (TL) technique. The age of flows ranges from ~2 to 100 ka and multiple TL analyses by the total bleach method yielded ages that overlap at one sigma with independent chronologic control. The TL signal of one sample of baked sediment beneath a lava flow with an inferred age of at least 641¿54 ka was near saturation, perhaps reflecting a relatively high environmental dose rate, and is not datable by TL. This study underscores several major limitations of luminescence geochronology, the natural spatial and temporal variability in environmental radioactivity and the susceptibility of silicate minerals to the growth and retention of a luminescence signal. Despite these limitations, the results demonstrate the utility of luminescence geochronology to date volcanic eruptive events during the Quaternary. ¿ American Geophysical Union 1994