This paper studies the ESG preferences of 401(K) investors after sustainability rating becomes readily available. We find significant heterogeneity in sustainabil- ity preferences with respect to opinions on climate change, political ideology and personal experience of abnormally warm weather among 401(K) investors. The heterogeneity is mostly in fund flows to the least sustainable funds. We also find that regulatory uncertainty in fiduciary duty prevents plans to cater to sustainable preference. Our study has important implications about the long-term future of ESG investing.