The professional growth of midwives, essential for optimizing midwifery leadership globally, can be enhanced through twinning collaborations. How twinning promotes growth is unclear. This case study explores how professional growth is affected by cultural differences between twins. We used a longitudinal qualitative design including data from open-ended questionnaires and focus groups. These data were analyzed using a content analysis. Our findings show that cultural differences were capable of both hindering and facilitating professional growth. Within the complex dynamics of twinning, professional growth was facilitated by twins’ preparedness to bridge cultural differences. Common goals positively influenced this process. Friction was more likely, and professional growth was hindered, when midwives were unprepared to bridge cultural differences. To optimize professional growth through twinning, we recommend a clear focus on common goals and consideration of the interaction between the length of a project and the extent of the cultural differences between twins.