The aim of this paper is to empirically investigate antecedents and outcomes of organizational unlearning and forgetting in the process of new product development (NPD) in teams. Through identifying antecedents of knowledge loss, we intend to find indicators and levers of control to successfully manage unlearning and forgetting processes. Our research should also reveal how these control mechanisms then reduce negative consequences and facilitate positive outcomes in the process of new product development. We employed a holistic multiple-case study design to examine our proposed research question. We conducted 30 individual semi-structured interviews in 10 different new product development teams (10 cases á 3 team members). Gathering additional data allowed us to triangulate our findings and propose a path model with unlearning and forgetting elements in the product development process. Our results indicate that managing unlearning and forgetting can increase a team’s performance, whereas disregarding the management of knowledge loss can lead to a decrease in group performance. The inability to unlearn (resistance to unlearning, stress, daily routines, or fear of making mistakes) and involuntary forgetting (faulty documentation and communication, key employees leaving the company, or information overload) are main drivers of knowledge loss in new product development. Organizations try to counteract negative consequences of knowledge loss by trying to encourage unlearning and diminish forgetting. Depending on the desired outcomes of an innovation, companies should promote unlearning and specifying degrees of freedom for individuals in NPD teams. Being attentive to unlearning and forgetting processes allows teams to be more flexible and receptive to change. Organizations should free team members from the shackles of daily routines to provide more time for identifying outdated and obsolete knowledge, which then can be actively unlearned. Also, companies should find ways to regulate knowledge inflows to protect their employees from information overload.