Balloon borne telescopes can achieve much of the promise of a satellite borne experiment, at a fraction of the cost, while providing important tests for upcoming satellite missions. I will discuss two balloon borne instruments: BLAST, a sub-mm telescope which hase made extensive maps looking at galaxactic and extragalactic star formation, and the upcoming Spider mission, which will measure the polarization of the cosmic microwave background in order to constrain models of inflation, and to probe the reionization of the Universe.