Hale, Jon. “Sustainability and Quality Go Hand in Hand - We find that funds with high sustainability ratings tend to have higher-quality holdings.” Morningstar, March 16, 2017.
Concluding paragraph: "[A] Morningstar Sustainability Rating of 5 globes tends to point investors to a subset of funds with better Morningstar Ratings (risk-adjusted return relative to category), better Morningstar Analyst Ratings (forward-looking analyst evaluation), lower volatility, and greater exposure to financially healthy companies with economic moats. It suggests that companies that are doing a good job addressing their ESG risks and opportunities tend to be quality companies and that funds that have a lot of those types of companies in their portfolios tend to be quality funds."
LK comment: The Morningstar globe ratings are based on data from Sustainalytics. I believe (summer 2018, opinion subject to change) that this link between various measures of corporate social/sustainability performance and the Morningstar moat rating is probably of fundamental importance, and not well understood. See also DiBartolomeo (2010) and Kurtz (2016).