Dark Matter (DM) provides strong evidence for physics beyond the Standard Model (SM). Arguably, rather than suggesting a specific mass scale for New Physics, it may point to a dark sector, weakly-coupled to the SM, as hinted at by the comparable abundances of dark matter and visible baryons. In the past few years, a program of new experiments has expanded DM searches far beyond the WIMP paradigm to include new hidden forces and matter. While this program has made impressive progress, there are considerable challenges that must be overcome to fully explore the viable dark sector scenarios over a wide range of mass scales. In this seminar, I will discuss new search strategies to test dark sectors at low-energy high-intensity experiments, with a special emphasis on existing and planned experiments at Fermilab. I will highlight the complementarity of these experiments with LHC searches and with DM direct and indirect detection experiments in probing the parameter space of well motivated models as, for example, models of Strongly Interacting Dark Matter or Inelastic Dark Matter.