The Square Kilometer Array is intended to be the centimeter- and meter-wavelength telescope for the 21st century. Originally proposed as the ``hydrogen telescope,'' the 21-cm hyperfine transition of H\,\textsc{i} continues to play a significant role in the Key Science Projects envisioned for the SKA. The 21-cm emission from galaxies will be used both as a means of tracking galaxy evolution over cosmic time as well as a tracer of mass for cosmological studies. The 21-cm emission and absorption from the intergalactic medium itself at the time of the Epoch of Reionization will be traced to follow the evolution of this crucial phase of the Universe's history. A number of telescopes, both those currently in operation and under construction, will provide crucial pathfinding developments, technically, algorithmically, and scientifically. I will summarize a number of recent developments toward the SKA, including the Reference Science Plan, intended to serve as a set of scientific requirements.