While we know that poor decisions during concept screening can lead to great expenses including redesign costs, production postponement, and even product failure, little is known about what factors influence professional concept screening. Previous research in this area has mostly been conducted with students or used hypothetical design challenges with professionals. This is problematic because such research methods are based on challengeable assumptions leaving out the risks and consequences that professionals face in their daily work. Hence, the purpose of the current study was to investigate the process of professionals making screening decisions in situ and identify the impact of the perceived properties of ideas (i.e., riskiness, originality, and feasibility) and the role of the professionals (idea generators versus executives) in this process. Specifically, a mixed method in-situ study was conducted in a small electromechanical company which included shadowing a research and development team from the conceptual stage to a final pitch meeting to senior executives. In addition, surveys and interviews were conducted to identify what factors were impacting concept screening. The results showed both idea generators and executives were able to distinguish and move ideas with relatively high market potential forward and avoided taking risks during concept screening. However, the idea generators did not show any preferences on the originality or feasibility of the ideas, while the executives preferred to invest in ideas with high feasibility. The findings of this study drew a distinction between professional design studies solving real design problems in a naturalistic, collocated team environment and those in a laboratory setting and added to the understanding of factors that influence the decisions made during professional concept screening. They also provide a much-needed insight into how engineering design professionals screen ideas .