Architectural heterogeneity has proven to be an effective design paradigm to cope with an ever-increasing demand for computational power within tight energy budgets, in virtually every computing domain. Programmable manycore accelerators are currently widely used not only in high-performance computing systems, but also in embedded devices, in which they operate as coprocessors under the control of a general-purpose CPU (the host processor). Clearly, such powerful hardware architectures are paired with sophisticated and complex software ecosystems, composed of operating systems, programming models plus associated runtime engines, and increasingly complex user applications with related libraries. System modeling has always played a key role in early architectural exploration or software development when the real hardware is not available. The necessity of efficiently coping with the huge HW/SW design space provided by the described heterogeneous Systems on Chip (SoCs) calls for advanced full-system simulation methodologies and tools, capable of assessing variousmetrics for the functional and nonfunctional properties of the target system. In this article, we describe VirtualSoC, a simulation tool targeting the full-system simulation of massively parallel heterogeneous SoCs. We also describe how VirtualSoC has been successfully adopted in several research projects.