Policy process scholars have exhibited a long-standing interest in policy evolution, but relatively underattended to in extant literature on this topic is assessment of how policy language changes over time. Evaluating policy evolution through analyses of changes in policy language lends understanding regarding the substantive aspects of policies that are adjusted over time. In this paper, we analyze changes in the text of net metering legislation in four US states. To do this, we leverage Ostrom’s Rule Types and the Institutional Grammar to operationalize micro-level policy change. More specifically, this paper takes a comparative case study approach to examine: (1) how can micro-level policy design features be systematically operationalized across cases and time periods, and (2) are there common patterns in the types of rule configurations and syntactic components of legislative texts that change over time (i.e., are substituted, added or removed). Our study offers an operationalization of common policy evolution dynamics (layering, packaging, and patching) at the micro-level. We also show how these dynamics can be observed differentially at different levels of analysis and suggest measurement should match the scholar’s or practitioner’s question. (Co-authored with Graham Ambrose, Myriam Gregoire-Zawilski, and Nicholas Oesterling)