This study examines how linguistic behavior (i.e., the communication style of two or more participants in online discourse) can affect compliance in the context of online health communities (OHC). Building on communication accommodation theory (CAT), we propose hypotheses of how convergent and divergent communication styles affect the behavior of opioid addicts. To assess the linguistic behavior between conversation participants, we situate our study in a unique online environment on Reddit where a large group of people is dedicated to helping each other address the addition problem. Constructing a panel dataset of posts of self-identified opioid addicts in the OHC, we estimate a fixed-effects model to assess the causal impact of linguistic behavior. To address endogeneity concerns associated with omitted variable bias and self-selection, we use a combination of identification methods based on two-stage least squares (2SLS) and coarsened exact matching (CEM). To validate our hypotheses, we conduct a randomized experiment (ongoing work). Our empirical results support our hypotheses indicating a positive effect of convergent and a negative effect of divergent communication styles on compliance. The results of the study contribute to literature on OHC, advance understanding of the role of CAT, and also provide practical recommendations to health and business practitioners.