Transdisciplinary research teams offer an appropriate alternative to traditional research methods to address today's complex research problems. However, a lack of common technical language and differing attitudes on collaborative research can create challenges. This paper reports results of an evaluative survey on changes of collaborative capacity within a large transdisciplinary project. CSCAP evaluator survey data collected from pre-assessment (2011) and mid-assessment (2013) evaluation surveys of project participants, measured participants' attitudes, behaviors, and beliefs regarding transdisciplinary research. Paired samples t-tests, and multiple regression analysis were employed to compare measures from the same individuals at two points in time and relationships between measures. The key variables were transdisciplinary attitudes, transdisciplinary behaviors, satisfaction with collaboration, perceived impacts of collaboration, and trust and respect. Changes over time were evaluated for the overall project team and by project role subgrouping that included principal investigators, professional and technical staff, graduate students, advisory board members, and extension educators. The analysis examined the following research questions: 1) Do participants' attitudes and behaviors toward the transdisciplinary process change over the course of the project? 2) Do these changes vary by participant role? 3) What factors are associated with changes in attitudes toward transdisciplinary research over time? Results indicate that while collaborative behaviors did not significantly change for most of the role subgroups, advisory board members showed a decrease in transdisciplinary behaviors from the pre-assessment to the mid-assessment evaluation. Analysis of the other measures consistently showed a positive increase in mean scores from the pre- to the mid- assessment with one exception. Graduate student scores on the transdisciplinary attitude scale decreased over time. Regression analysis showed a relationship between TD attitudes and the trust and respect measure. Understanding how participant perceptions may change over the course of a project and how project roles may influence these changes is important to managing effective long-term transdisciplinary projects.