The insufficient understanding and literature on people collaborating in the Architectural-Engineering-Construction (AEC) industry has prompted researchers to investigate this by conducting project-to-project comparisons. A mixed method-based comparison of two construction projects’ design teams was made in order to present factors to be considered in fostering a positive collaborative culture. Client knowledge and involvement, existing relationships between teams, stronger informal collaboration, a decentralised leadership style and the adequate monetary motivation to a firm were found to be most critical. The study also assessed whether the use of holistic analysis methods can quantitatively show the differences between the projects; in particular, which project had a more positive collaborative culture. The perception based method used correlated the variance of perception of the teamwork environment and systemic risk to the projects with a more positive collaborative culture; 80% of constructs (some postulated attribute of people assumed, to reflect in test performance) supported the qualitative data. Additionally, assessments of the personalities of respondents from the project with a more collaborative culture also showed higher collective agreeableness. Findings suggest that projects with more changes, more assumptions made and uncertainty in requirements affect the collaborative culture negatively.