Background: Nurses are commonly promoted to the role of nurse manager based on clinical competency rather than managerial skill or operational knowledge. The clinical nurse stepping into a managerial role may take up to seven years to develop the competency required to confidently perform in their new role. The transition from clinician to leader and manager, requires a structured development approach. Objectives: Leadership development for the nurse manager has a long-term impact with positive results within six to nine months after training. The nurse managers left to seek the development of their own competency are likely to find workarounds, but nurse managers offered formal leadership development are more likely to implement a culture of evidence-based practice and improved outcomes. Methods: Fourteen nurse managers, with less than seven years of experience in a managerial role within an acute care hospital setting, completed a nine-week structured development program. A pre- and post-competency assessment was conducted using the Nurse Manager Skills Inventory Tool to measure self-assessed knowledge in three domains: the science of managing the business, the art of leading people, and the leader within. Results: Thirteen out of fourteen participants completed the nine-week intervention program. Twelve out of thirteen submitted a pre- and post- competency self-assessment. The results reflected an improved mean score of self-assessed competency in all three domains. Domain 1: The science of managing the business had the greatest growth with a pre-intervention mean score of 1.78 � 0.83 to a 2.45 � 0.75 post-intervention. Domain 3: The leader within reflected the least growth with a pre-intervention mean score of 2.34 � 0.77 and a post-intervention mean score of 2.69 � 0.65. Two of three domains proved significant results with p value <0.05: the science of managing the business with and the art of leading people. Conclusion: A structured development program enhances self-assessed competency for the nurse manager adapting to a new role. Nurse managers influence work environments which impact recruitment and retention, patient outcomes, workflows, organizational goals and financial wellbeing. Investing in nurse manager development is an essential element to an organization’s operational success, patient safety, and quality of care.