This mixed methods descriptive case study explored the perceptions of 162 leaders and French immersion (FI) teachers related to their roles and responsibilities for the target-language proficiency (TLP) of FI teachers in an urban school division. To date, no research has explored leaders' and FI teachers' knowledge and understanding of the system as it relates to TLP. Results revealed inconsistent knowledge of university requirements, provincial requirements, and hiring and evaluation practices pertaining to the TLP of FI teachers. Although leaders (94%) and FI teachers (93%) agreed that the TLP of FI teachers was very important and further agreed that ongoing development of TLP was essential throughout FI teachers' careers, data indicated that only 60% of FI teachers would consider participating in activities related to the ongoing development of TLP if the division offered them. The study confirmed obstacles such as time and the need to focus on other types of professional learning beyond TLP, as previously noted in the literature. Additionally, this study added to the body of literature by identifying the perceived responsibilities of leaders and FI teachers related to their responsibilities for the TLP of FI teachers. Results were analyzed using Senge's learning organization framework. The results and implications of this study may provide insight for school divisions about ensuring that TLP is viewed as a shared responsibility that is articulated and actioned in procedure and practice. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]