On January 1, 2022, mandatory genetically engineered (GE) food disclosure labeling will be required nationwide in the United States. To date, the only mandatory GE labeling law implemented in the U.S. was Act 120 in Vermont. This thesis examines the consumer purchasing response to the implementation of Vermont Act 120 using store-level scanner data of food purchases. I measure the effects of Vermont Act 120 on the grocery store sales of non-GMO, organic, and GE- labeled products in Vermont. Using a difference-in-difference approach, I can compare stores in Vermont to control states before and after the law was passed, implemented, and repealed. I find that during the implementation period, sales of non-GMO and organic labeled products increased, and the sales of GE-labeled products decreased. The sales trend reverted after the law was repealed but not quite to the baseline levels for organic and GE-labeled products.