For those philosophers of space and time inclined towards a structuralist, third-way approach to ontology, Newton's defense of the immobility of the parts of space is often regarded as a powerful historical precedent, prompting a host of structuralist-leaning commentary over the past several decades. Newton's arguments, which appear in his early De grav and the Principia's scholium on space and time, have been analyzed by Stein, DiSalle, Healey, Torretti, and many others committed to a more nuanced spatial ontology than traditional substantivalism and relationism offer. Recently, however, there have appeared two important assessments, by Nerlich and Huggett, that question whether Newton's structuralist or holistic conception of the identity of spatial parts ultimately undermines his overall conception of space, a problem that, interestingly, does not appear to be a connected with his espoused absolutism or alleged substantivalism. Since Newton bases the identity of the parts of space on their structural relationships, and since all the parts of his infinite Euclidean space manifest the same structural relationships with one another, do these parts thereby lack the necessary identity criterion for a coherent theory of space? In order to better grasp Newton's arguments and his general conception of these issues, this chapter will explore the background of, and the possible sources of influence on, Newton's theory of the identity of spatial parts, as well as critique several important interpretations and arguments put forward by commentators. Yet, this chapter is not limited to an historical examination of seventeenth century theories alone, since a contemporary analogue of the problems associated with Newton's treatment of the identity of spatial parts finds a home in contemporary spacetime debates. The goal of this chapter, consequently, is two-fold: first, we will rebut the problems raised by both Nerlich and Huggett by means of a more intricate historical and philosophical analysis of the spatial holism intrinsic to Newton's theory; second, we will argue that modern debates on the ontology of spacetime, some of which have been motivated by similar puzzles, have either unwittingly followed, or could benefit from, Newton's holistic conception of spatial ontology.