When the cities of San Francisco and Boston banned the sale of tobacco in retail pharmacies, the number of cigarette buyers fell by 13%. Indeed, making cigarettes even slightly less accessible can push down childhood smoking rates. Which is why CVS Health’s decision, in early 2014, to stop selling tobacco products in its 7,600 stores was so momentous, and praised by public health officials. Investors have joined the chorus of hosannas, pushing CVS stock up 66% since the bold move—three times the return of the S&P 500 over the same period.