This study sought to develop and validate an instrument to test the self-efficacy of teaching engineering design. This study is part of a larger effort to develop an instrument for both pre-service and in-service teachers of Science, Technology, and Engineering education. The focus of this study is on the initial instrument creation process and validation with in-service teachers in Technology and Engineering education. A linear regression model found a significant association between the composite score (F(2,78)=6.469, p=0.003, R[superscipt 2] =0.142) and experience teaching engineering design and general teaching experience as independent variables. Experience teaching engineering design (t=3.566, p=0.001) and general teaching experience (t=- 2.087, p=0.040) were both significant predictors, with experience teaching engineering design being significant at a higher level. The dual experience model is preferred over a model with just teaching engineering design as the independent variable (F(1,79)=8.232, p=0.005, R[superscipt 2] =0.083) although both models show a significant association with the composite score. A one-way ANOVA showed no significant differences based upon gender, although there were significantly different samples sizes between males (n=57) and females (n=24). Levene's test indicated that the homogeneity of variance assumption was met. The initial findings from this study indicate that a case for validity may be made. A second confirmatory study will be needed but falls outside of the scope of this study. [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.]