Do institutional investors shape how firms respond to competitors' CSR commitments and policy adoptions? We find that despite negative initial market reactions, long-term investors persuade peer firms to mimic voting firms' adoption of close-call CSR proposals in the year following their passage. Such peer imitation positively impacts peer firms' value by reducing cash flow risk, particularly for those with a relatively higher long-term institutional ownership. Smaller, younger, weaker and firms in more competitive industries benefit more, which can be explained by the learning motive.