This volume, the first devoted specifically to Speusippus in English, offers a new picture of Speusippus' philosophy via an in-depth analysis of the testimonia preserved by Aristotle. The book develops a new methodology for understanding the evidence concerning authors of the Early Academy, Speusippus in particular, providing a fresh assessment of the initial phase of Platonism, which calls into question the long-held view that Speusippus was a distinct outlier among Platonists. By reconstructing discussions within the Academy, looking at Aristotle especially, we can better understand the presence of Speusippus' doctrinal deviation from or preservation of Plato's doctrine as the effort of a genuine Platonist - the first - to re-shape his Platonic credentials in the backdrop of Aristotle's critiques. In offering a new reconstruction of the philosophical views of Speusippus, the book provides new points of departure for research on the Early Academy and challenges previous ideas regarding the early development of Platonism. Speusippus: A Forgotten Voice of Platonism is of interest to students and scholars of Speusippus, as well as those working on Platonism, the Academy, and ancient philosophy more broadly.