This report describes the development of WinSMASH2010, an extensive update and enhancement to the WinSMASH crash reconstruction code. The specific objectives were (1) to correct known programming bugs in the original WinSMASH, (2) convert the code from the obsolete Delphi language to C-Sharp to allow future upgrades, and (3) to enhance WinSMASH accuracy by implementing an automated method of selecting vehicle specific stiffness coefficients.