Leveraging Online Search Data as a Source of Marketing Insights is written with two main audiences in mind. For practitioners, it offers a guide on how best to utilize platforms such as Google Trends and extract actionable insights for a wide array of business decisions illustrated with real-world example applications. For academics, it provides a literature review and a framework that integrates the various avenues through which online search data can be leveraged in scientific research. The monograph starts with a brief tutorial of Google Trends and Google Ads Keyword Planner, two popular platforms for gathering online search trends and volume data, respectively. It also briefly discusses Baidu Index as an alternative to Google Trends for insights about the Chinese market, where Baidu is the dominant search engine. The next section offers a review of the literature that has utilized online search data. First, it surveys research that has treated aggregate online search interests as either concurrent or leading indicators of real-world phenomena. Second, it examines research that has treated online search data as response variables that can help measure and improve marketing effectiveness in terms of both immediate and longer-term impacts. Third, it reviews research that has treated patterns of online searches as unvarnished reflections of the public psyche, uncovering what people really think, feel, and intend to do, insights that may otherwise be difficult to ascertain based on what people post on social media or tell market researchers in surveys. The authors conclude by highlighting several promising areas for future research where online search data can serve as a big-data supplement to traditional market research.