Aim: To investigate transition in newly qualified nurses through an exploration of their stressors and stress experiences during their first 12 months postqualifying. Background: Globally, thousands of new nurses qualify annually. They are crucial for the profession and healthcare service delivery. Work-related stress has multiple serious consequences, yet there is a lack of robust, empirical evidence that directly analyses newly qualified nurses and the stress they feel and experience in the work-place. Understanding what causes newly qualified nurses' stress is vital to retaining and nurturing this vital component of the workforce. Design: Longitudinal, explanatory sequential mixed methods, cohort study. Methods: At the point of qualification (n = 288), 6 months postqualifying (n = 107) and 12 months postqualifying (n = 86), newly qualified nurses completed the Nursing Stress Scale, with 14 completing a one-to-one interview at 12 months postqualifying. Data were collected from 2010 -2012. Inferential statistics, "thematic analysis" and "side-by-side comparisons in a discussion" were used for analysis. Results: Workload was consistently the highest reported stressor with inadequate staffing and managing multiple role demands given as explanations. Incivility within the workplace was a noted stressor. Conversely, being part of "a good team" provided a civil, supportive, facilitative work environment. Entering nurse education with previous healthcare experience had a mediating effect on the reported frequency of stressors. Conclusions: Newly qualified nurses encounter multiple work-related stressors over their first 12 months postqualifying, which are intrinsically entwined with their transition. Employing organizations need to be more proactive in managing their workload and addressing workplace incivility.