The discovery of superconductivity in iron-pnictide materials has generated much excitement in the past year about possibly unifying mechanisms for high-temperature superconductivity. In particular intriguing effects have been noted with the application of pressure to these materials, with novel structures and magnetic order appearing. CaFe2As2 is the parent compound to a family of superconductors, and the effect of pressure is most dramatic, with a first order phase transition into a so-called "collapsed" structure. We propose to study the transitions between phases under applied pressure, paying particular attention to structural changes and coexistence in regions of large hysteresis. We hope to determine precisely how the bond lengths and angles change during these transitions, as this may be key to understanding the role the structure plays in superconductivity.