At a small, private school in the southern US, an elective first-year design (FYD) course is offered in addition to the required capstone design course; both courses challenge student teams to tackle real-world problems. In FYD, positive team member effectiveness is cultivated through teaming instruction, demonstrations, and practice. In this study, we hypothesize whether teaming skills gained in FYD are evident in capstone design. Using a linear mixed effects model, we measure the impact of participation in FYD on teaming performance of 431 students in capstone design. Values of specific teaming skills and values of overall team member effectiveness of individuals on teams are captured using the on-line peer-evaluation tool CATME (www.catme.org). Students who participate in FYD have statistically significantly higher scores in three (of five) basic teaming skills evaluated through CATME: interacting with teammates; expecting quality; and having related knowledge, skills, and abilities. Students who participate in FYD have statistically significantly higher values for overall team member effectiveness and higher overall team member effectiveness during the first, but not the second, semester in capstone design. This longitudinal study is the first to evaluate the long-term impact of a first-year design experience regarding teaming skills, and these results add to a body of literature supporting the call for intensive early teaming experiences needed later in professional settings.