Interpersonal skills and perfectionistic tendencies of gifted adolescents may influence psychological health and future professional success. In order to better understand these variables, we must have accurate and valid measures first. This study attempted development and validation of measures of interpersonal skills and perfectionistic tendencies among gifted children in order to determine if the constructs had quantitative and qualitative meaning. Gifted students' responses to the Interpersonal Competence Questionnaires (ICQ) and Frost's Multidimensional Perfectionism Scale (FMPS) were analyzed with the Rasch rating scale model. Evidences of multiple aspects of validity were examined in order to make evaluation judgments regarding the validity of the measures. Initial Rasch analysis demonstrated that both ICQ and FMPS have poor rating scale functioning, dimensionality and person fit statistics. Modifications were made to the original scales, including collapsing rating scale categories, deleting misfitting items and misfitting people. Two new measures, ICQ-revised and FMPS-revised, were generated based on the initial results from Rasch analysis. According to the Rasch diagnostic indices, the ICQ-revised and FMPS-revised demonstrated adequate reliability, separation, item and person fit, rating scale functioning, and dimensionality. The cumulative evidence from this study allowed for concluding that measuring gifted students' interpersonal skills and perfectionistic tendencies were desirable using the revised measures. However, further investigations into the theoretical framework of these two constructs among gifted students were still needed to improve the scales to target students with advanced interpersonal skills and higher level of perfectionistic tendencies. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]