Invasive species can cause significant changes to their introduced environments. A set of experiments was conducted to determine whether Sapium sebiferum exhibits allelopathic effects on neighboring plants in its introduced range. Bioassays were performed on Sapium, Liquidambar styraciflua, Schizachyrium scoparium, Andropogon ischaemum, and Lolium perenne seeds using extracts from Sapium, Acer saccharinum, Platanus occidentalis and Liquidambar leaves. Germination and early growth comparisons were made using: (1) solutions treated with activated carbon to remove allelochemicals or left untreated, (2) solutions in a dilution series, and (3) solution mixtures prepared from rinsed leaves or soaked leaves using activated carbon to negate potential allelopathic effects of all but one leaf species in each mixture. In almost every analysis there were few significant predictors. The effects of Sapium extracts on germination or growth never differed from those of the three native tree species' extracts. Allelopathy does not appear to contribute to Sapium's invasive success.