Self-citations, where the citing and cited paper have at least one author in common, account for a substantial share of all academic citations. The cumulative nature of scientific research perhaps makes this kind of embedding a natural part of the communication process as writers’ earlier work informs their current research (e.g. Costas et al., 2010). Equally, however, the practice is often condemned as vanity and self-promotion; claiming an author’s scientific authority or gaming a system which rewards citation. Because of this, there have been calls to exclude them from the statistics which measure the impact of academic literature and which, in turn, contribute to tenure, promotion and funding decisions (e.g. Fowler & Aksnes, 2007). Despite this controversy, the citation indexes generally include self-citations and, as research becomes ever more specialized, co-authorship more common and competition to get published more intense, self-citation may now be a more significant rhetorical and tactical tool in the struggle for visibility and authority. In this chapter we examine this idea, tracing patterns of self-citation in the four disciplines of our corpora over a 50-year span, attempting to account for the changes that have occurred and give a rhetorical explanation for them.