The purpose of this dissertation is to explore the concepts of issue legitimacy and organizational legitimacy in an issue management context, providing empirical data when little has existed previously. To do so, this dissertation used two studies to explore the trend and features of issue legitimacy of DTC-ads, construction of organizational legitimacy and issue legitimacy, and effectiveness of issues management strategies on perceptions of organizational legitimacy and issue legitimacy. More specifically, Study 1 investigates issue legitimacy of DTC-ads on societal level employing a content analysis. Study 2 develops the measurement of organizational legitimacy and issue legitimacy on the individual level through the use of a statewide survey among Alabama residents, and examines the effect of issues management strategies on organizational legitimacy, issue legitimacy and behavioral intentions toward an organization by employing a 1 within- 2 (CSR: use of CSR versus no use of CSR) × 2 (Issue advocacy: use of advocacy framing versus no use of advocacy framing) × 2 (Self-regulation: use of self-regulation versus no use of self-regulation) quasi-experimental between-subject design. The findings from Study 1 present the trend of issue legitimacy of DTC-ads: moderate illegitimacy - illegitimation - increasing legitimation, and confirm the gap between issue legitimacy of DTC-ads in media coverage and organizational issue advocacy of the pharmaceutical industry. From the findings from Study 2, five measurement items for organizational legitimacy and six measurement items for issue legitimacy are found to be reliable and valid. The findings from an experiment show that the uses of CSR activity, issue advocacy, and self-regulation in corporate messages have influences on organizational legitimacy. However, only the use of self-regulation had significant differences on both perceptions of issue legitimacy and organizational legitimacy. Also the finding empirically confirms the importance of organizational legitimacy and issue legitimacy to organizational success in terms of purchasing intention.