Buy online, pick-up in store is often heralded as the future of retail: Customers shopping on their own terms, as efficiently as possible. But it might end up being a bigger lift than expected for retail stores. Large retailers like Target, Walmart, Kroger and Home Depot are using store pickup to cut delivery costs, encourage customer interaction with associates, and drive in-store sales growth. Using stores to fulfill online orders lets retailers add supply chain muscle to their e-commerce businesses. But it does come with risks. As demand grows for in-store pickup, in-store fulfillment could put pressure on traditional store operations.