Nanoscale self-assembly arises from and is highly sensitive to interactions among the assembling components and between them and their environment. Environmental complexities, such as spatial and temporal heterogeneities, are ubiquitous in self-assembling biological systems and materials processing protocols, yet our understanding of how they influence the assembly process remains limited. Our group uses numerical simulations to investigate how particles self-organize within these complex environments. Specifically, this talk will describe our investigations into the self-assembly of mixed ligand monolayers on the surfaces of faceted nanoparticles, the self-assembly of viral capsids within oscillatory environments, and the emergent self-organization of nascent oligomers during step-growth copolymerizations.