Electron paramagnetic resonance (EPR) is a powerful and commonly used probe of the electronic structure of metal complexes, in particular metalloproteins. However, due to a lack of appropriate software, many researchers using EPR have not benefitted from the rapid advance of affordable desktop computing power. During Phase I, a prototype software tool named WEPR was developed and demonstrated. This tool enables quantitative analysis of complex EPR spectra to be achieved routinely. The Phase I prototype applies to Kramers systems (half-integer spin) with isolated doublets. Phase II goals are: 1) expansion of the theoretical model to exact solutions for half-integer spin more 1/2 and integer spin, 2) adaptation to hardware with more computing capacity to better model the capacity of the hardware expected to be common in laboratories when this software will be widely marketed, and 3)development of means to facilitate use of the program by a wide segment of lab personnel including user's manual, on-line help and a more intuitive user interface. Compared with the current situation in EPR spectroscopy, such commercial software would allow more chemists and biochemists to analyze a broader range of paramagnetic complexes.