Unforced errors are a significant issue in producing high performance in tennis. Identifying the causes of these errors in important to guide interventions to reduce unforced errors. The purpose of this study was to examine the different causes of unforced errors (UE) of Women’s Collegiate tennis players from the perspectives of coaches and players. Specifically, and based on previous research (Hirata, Sato, Murakami, Sato, & Saijo, in press; Shibahara, Tamaki, Hirata, Sonobe, Morii, & Saijo, 2015), a measure was developed to collect data on UE. The factor structure was examined using data collected from 283 Collegiate women tennis players and 77 coaches of women tennis players. These participants were divided into High-Skilled (HS) and Low- Skilled (LS), where the criteria for such selection was based in the competition level played in different Competitions. In order to access the HS competition, players needed to be winners of the LS competition. Comparing and contrasting both groups are in the basis of the current research study.