The aim of this guide is to provide a starting point for using web archives as a source for social science research. With the migration of many aspects of the so- cial world online, fundamental questions have been raised about how and even when social science research happens in the online sphere (Karpf, 2012). Web archives, or archives of content and communications from the Web through time, crucially provide the means for retrospectively studying dynamic media and online interactions that are often subject to change and deletion. In addition to the opportunities afforded by web archives as a primary source, however, given their scale and complexity, these collections also present challenges for researchers who want to use them. This guide provides a primer for how to approach web archives research design by first outlining what web archives are and how they differ from other types of web data, as well as identifying key sources for web archives collections. Following this, we provide several high-level descriptions and examples of existing research to demonstrate how web archives offer particular methodological opportunities for studying different types of web phenomena. Next, we draw on the literature to highlight three key considerations for designing a project using web archives, including the ethical implications of using archived web data without the consent of content producers. The guide concludes by summarising the opportunities and challenges of using web archives and provides additional sources to consult.