This research presents the results from the development of the Personal Control Inventory (PCI). The PCI was based on the systems-based theory of perceptual control developed by Powers (1973). The PCI was developed in an Internet-based format using both coarse-grain and fine-grain Likert-type response options. Correlations, regressions and analyses of variance between comparison measures of depression, hope, psychological well-being and the PCI were performed. Item-level variability of the PCI from multiple administrations was evaluated for predictive ability for the depression measure. Graphic modeling representations were performed between the PCI and pre/post test scores on the comparison measures. Results suggested that the PCI was a reliable and valid measure of positive affect. The usefulness of graphical representations of systemic data are discussed as are the implications for research regarding the psychometric properties of the coarse and fine-grain response formats in Internet-based assessments.