Engineering design serves as the capstone experience of most undergraduate engineering programs. One of the key elements of the engineering design process is the compilation of results obtained into a technical report that can be shared and distributed to interested stakeholders including industry, faculty members and other relevant parties. In an effort to expand the tools available for assessment of engineering design technical reports, this study performed an initial validation of a previously developed Technical Writing rubric. The rubric was evaluated for its reliability to measure the intended construct, inter-rater reliability and external validity in comparison to an existing generalized written communication rubric. It was found that the rubric was reliable with Cronbach’s alpha for all dimensions between 0.817 and 0.976. The inter-rater reliability for the overall instrument was also found to be excellent at 0.85. Finally, it was observed that there were no statistically significant differences observed between the measurements obtained on the Technical Writing rubric in comparison to the more generalized Written Communication Value rubric. This demonstrates that although specific to engineering design environments the Technical Writing rubric was able to measure key constructs associated with written communication practice. This rubric can now serve as one additional tool for assessment of communication skills within engineering capstone design experiences.