The topic of assertion has recently received a fresh wave of interest from Peirce scholars.Approaches have ranged from showcasing Peirce's responses to particular problematic assertions to investigating the possible power of a Peircean commitment view of assertion in the scheme of the contemporary landscape (Atkins 2011, Heney 2015, Boyd 2016. These newer efforts add to the insights of the important papers of the past, including Brock (1981), Martens (1981), andHilpinen (1982). However, to this point, no systematic account of Peirce's view of assertion has been attempted. We think that this is a lacuna that ought to be filled. Doing so will help make better sense of Peirce's pragmatism; further, what is hidden amongst various fragments is a robust pragmatist theory of assertion with unique characteristics that may have significant contemporary value. Here we aim to uncover this theory, and to show that assertion for Peirce is not a mere corollary of pragmatic conceptions of truth, judgment, and belief, but is rather a central aspect of his philosophy.One good reason why it is difficult to give a systematic account of assertion for Peirce is that it is a topic that Peirce himself treated in an unsystematic way. We have thus set ourselves two tasks. The first is to bring to order Peirce's often scattered and incomplete thoughts about assertion. As we argue in section I, Peirce's remarks about assertion span a significant amount of his career, so it is worthwhile to get a sense of their order and development. Our second and most