This 3-year longitudinal qualitative study explored the effects of supernumerary status and mentorship on student nurses undertaking the Project 2000 programme. The Project 2000 programme was the United Kingdom’s Nursing and Midwifery professional body’s way of providing consistency in the delivery of nurse training across the United Kingdom. I adopted grounded theory as the research method for this study because in 1992, little was known about how nursing students undertaking the new Project 2000 programme learnt in the clinical practice setting, and grounded theory is considered well-suited to research where little is known about the topic of study. The longitudinal nature of the study allowed the students to be followed through the 3 years of their programme (until they became qualified as staff nurses). Data collection occurred between October 1993 and September 2006. Ten students volunteered to be interviewed five times throughout their programme and to keep an on-going reflective diary to record their thoughts and experiences during their clinical practice placements with specific focus on supernumerary status and having a mentor. The diary acted as an aide memoir during each interview. Seven additional students volunteered to participate by diary only. These students kept written accounts of their experience of having supernumerary status and having a mentor while they were in their clinical practice placements. Data were collected and analysed using constant comparative method, a signature feature of grounded theory. Through constant comparison over the 3 years of data collection and analysis, a number of major categories and a core category emerged.