Even though eco-labels are a promising means to support consumers in making sustainable choices, insights into the effectiveness of eco-labels in combination with conventional marketing tools are scarce. This field study (a) investigates the effect of eco-labels on consumers' actual purchase behavior in an online fashion store, (b) examines the moderating role of price premiums, and (c) reveals a three-way interaction between eco-labels, price premiums, and discounts. Based on 58,000 actual purchase decisions from a large-scale field experiment, the results indicate a beneficial effect of eco-labels on consumer purchases and that higher price premiums can even reinforce the positive effect of eco-labels. The empirical findings also suggest that discounts only increase purchases for eco-labeled products in combination with high price premiums, but not with low price premiums. The present study has important implications for research on eco-labels and their interplay with other marketing cues and provides valuable guidance to marketers and policymakers on how to price eco-labeled products.