Theory suggests that balance sheet information such as total assets, total equity, or total liabilities complements earnings information in helping investors assess a firm’s profitability and estimate earnings growth. The voluntary disclosure of balance sheet information at earnings announcement could help investors gather and process this information at a lower cost. We therefore predict that voluntary balance sheet disclosure at the time of an earnings announcement helps investors promptly understand the implication of current earnings news for future earnings and subsequently reduces post-earnings-announcement drift (PEAD). Consistent with these predictions, our results show that when firms provide voluntary balance sheet disclosures, the earnings response coefficient in the event window is significantly higher and the corresponding PEAD is significantly lower. We further find that the impact of voluntary balance sheet disclosure on PEAD is more pronounced when the magnitude of balance sheet value surprise is larger, when balance sheet value is more informative about future earnings, when earnings uncertainty is higher, or when information cost is higher, consistent with our conjectures that helping investors to better understand future earnings performance and lowering information costs are key mechanisms underlying the effect of voluntary balance sheet disclosure on PEAD.