Despite large scale application of performance- and risk management practices, project organisations struggle with responding adequately to early warning signs of project problems. This research investigates the main barriers in responding to early warning signs, and provides recommendations on how to deal with them, in order to stimulate the responsiveness to early warning signs. It is approached by a combination of mixed qualitative research methods including expert interviews, expert meetings and a case study. The results show that soft factors are underrepresented in applied project control methods. Furthermore, experts regard optimism bias, time pressure, project complexity and uncertainty avoidance as the most important barriers in responding to early warning signs. Also, the results demonstrate the occurrence and functioning of barriers in three rail projects in the Netherlands. It is concluded that in order to improve the ability to respond to EW signs, more attention should be paid to soft, managerial aspects, and the presence of barriers in responding should be taken actively into account. The responsiveness to EW signs is stimulated by taking more and effective time for reflection, by be stimulating and facilitating communication on early warning signs, and changing behaviour in decision-making in projects. The soft character of early warning signs and barriers, both occurring throughout the project environment, shows that cultural change in projects is necessary to achieve this. A set of recommendations is provided as starting points to facilitate the required change. This research contributes to scientific knowledge of early signs in project management by enriching the concepts of early warning signs and barriers in responding. It also contributes to practical knowledge in the industry by demonstrating the occurrence of barriers in construction projects.