To mitigate nurse shortages, health care decision makers tend to employ retention strategies that assume nurses employed in full-time, part-time, or casual positions and working in different sectors have similar preferences for work. However, this assumption has not been validated in the literature. The relationship between a nurse's propensity to exit the nurse profession in Ontario and employment status was explored by building an extended Cox Proportional Hazards Regression Model using a counting process technique. The differential exit patterns between part-time and casual nurses suggest that the common practice of treating part-time and casual nurses as equivalent is misleading. Health care decision makers should consider nurse retention strategies specifically targeting casual nurses because this segment of the profession is at the greatest risk of leaving. Nurse executives and nurse managers should investigate the different work preferences of part-time and casual nurses to devise tailored rather than "one-size fits all" nurse retention strategies to retain casual nurses.