This study examines the influence of the media environment on advertising (a.k.a., the media engagement effect) a factor that is suggested to be considered in media decisions. Even though it has been the subject of interest for media practitioners and scholars for more than 50 years, there remains a lack of understanding of this research area and an abundance of mixed results. Thus, this study aims to: 1) comprehensively review how media engagement has been studied in the literature, focusing on terms and definitions about the media engagement effect and theories considered to explain the effect; 2) examine the relationship between media context and ad effectiveness and determine when the relationship varies; and 3) identify which media context enhances or harms ad effectiveness.In this study, 234 manuscripts were identified from 1960 to 2013 and examined using a systematic review and a meta-analysis. The majority of articles were journal publications that investigated the impact of media context on advertising in the TV context. More than half of the studies were conducted using experiment methods, and college students were most frequently recruited as study participants. This study found: A number of terms appeared in the literature to refer to media engagement. Earlier definitions of the terms tended to emphasize the values that media classes or vehicles possess, whereas later definitions emphasize the changes in consumers as a result of consumers engagement with media prior to advertising exposure. About 133 theories were considered the foundation to explain why and how media engagement effect occurs, indicating this effect is a complicated phenomenon. Approximately 70 different media context variables were used, and about 15 different ad effectiveness measures were examined. The overall relationship between media context and ad effectiveness was weak, but the effect differed by specific media contexts and ad effectiveness measures.The importance of these findings and implications of the results are discussed. Limitations and future research directions are also presented.