Complexity is a major problem for managers and decision-makers and needs to be addressed for projects to succeed. The aim of this study was to explore the factors contributing to complexity and project failure and success. An online cross-sectional survey of 114 researchers, project managers and decision-makers was conducted to explore these factors. Results showed that all participants who use project management indicated that it contributes to the success of their projects. Humans and human interactions were chosen by most participants as the main factor responsible for complexity. Most participants indicated that poor communication and collaboration was the biggest factor preventing them from achieving their goals. Participants mostly prefer working with people that they have a lot in common with, and most indicated that smaller teams of four to five people are better for optimal performance compared with larger team sizes. Feeling valued, respected, and being adequately rewarded motivated participants to perform well. In conclusion, project management may be able to improve the chances of project success. Addressing human factors and interactions may reduce complexity and motivate people to perform well. Limitations of this research include convenience sampling and subjective responses to a cross-sectional survey rather than objective measurement of outcomes.