The Impostor Phenomenon (IP) is a pervasive psychological condition characterized by self-doubt and a fear of being exposed as a fraud, despite evidence of one’s competence. This condition is particularly prevalent in high-pressure fields such as software engineering, where constant innovation and expertise are demanded. An initial survey of 624 software engineering professionals across 26 countries revealed that more than half experience frequent and intense impostor feelings, negatively impacting mental health and productivity. To address this concern, this Ph.D. thesis seeks to identify key factors driving IP’s prevalence in software engineering and develop targeted strategies for its mitigation. Using a mixed-methods approach, this research combines quantitative survey data from the prior study with in-depth qualitative interviews to provide a comprehensive understanding of IP within the software industry. Based on this understanding, the research will examine mitigation strategies from other fields, adapt them to the unique demands of software engineering, and empirically assess their effectiveness, evolving our knowledge on how software professionals can be best supported. Expected contributions include a detailed analysis of IP’s underlying factors in software engineering and the development of innovative and tailored interventions to reduce impostor feelings in software professionals. The findings are expected to have relevant implications for both industry and academia, fostering psychologically safe environments that enhance well-being and productivity and laying the groundwork for future advancements in workplace support and mental health for software professionals.