Abstract: I will discuss recent work on star forming, HI-dominated environments from nearby, low-mass dwarf galaxies to extended ultraviolet (XUV) disks. In both cases, stars are forming at low levels -- requiring interstellar media capable of doing so -- but the gas columns and molecular fractions in these regions can differ substantially from those in the main disks of normal, star forming galaxies. I'll present some ongoing studies of the gas available for stars to form in these very different environments and discuss their broader context by comparing to more typically studied star forming gas. Finally, I will address the evolutionary context of these environments, as they are great examples of the ways in which atomic gas affects the ongoing evolution of galaxies of all sizes.