Methods and apparatus related to automatically rewriting a string of text utilizing one or more rewrite rules. Some implementations are directed to scoring rewrite rules based at least in part on user interactions with rewrites that are generated by applying the rewrite rules. Some implementations are directed to determining the effectiveness of a rewrite generated based on applying one or more rewrite rules to a string of text. In some of those implementations, the determination may be based at least in part on one or more characteristics of the string of text, one or more characteristics of the rewrite, and/or scores associated with the rewrite rules.