Abstract. I will discuss the physics of dark matter models featuring composite bound states carrying a large conserved dark "nucleon" number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and we find that this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. > 10^8, are synthesised, with the number distribution taking one of two characteristic forms, independent of many details of the initial conditions and small-number interactions. I will also briefly discuss the constraints arising from the novel dark sector energetics, possible modifications to astrophysical processes, and the potential direct detection signals.