Aim The aim of this research study was to establish the effects of classroom learning and \nclinical practice on the development of self-confidence amongst undergraduate nursing \nstudents in Ireland. \nBackground \nSelf-confidence underpins nurses' competence to carry out care effectively and is an \nimportant aspect of learning to be a nurse. Yet, there is little empirical evidence that \ndemonstrates its full utility in nursing, and, to date, no evidence addressed how selfconfidence \ndevelops from the students' perspectives or the impact of clinical practice on \nstudents' self-confidence. \nMethod \nThis study examined the extent to which theoretical preparation and clinical practice \ninfluenced self-confidence among first-year undergraduate nursing students in Ireland. This \nwas achieved through a sequential, mixed methods, three-phase design that involved pretest \nand post-test measurements of self-confidence, a student self-evaluation questionnaire \n(SSEQ), focus group interviews and an analysis of the relevant curriculum content. The study \nwas underpinned by Bandura's Social Learning theoretical model. The sample was taken \nfrom three cohorts of students at three institutes of technology in Ireland. Data analysis \nincluded descriptive statistics, inferential statistics, and qualitative content analysis. \nResults \nA two-stage model was developed that identified how self-confidence was influenced in the \nclinical and non-clinical environments. Factors in clinical practice exerted the most influence. \nSelf-confidence was promoted particularly through positive preceptorship experiences, peer \ninfluence and successful mastery experiences of clinical practice. It was instilled through a \nsense of trust, recognition of performance, constructive feedback, and being made to feel \npart of the team. Self-confidence fluctuated during the first clinical placement, and, as \nnursing students' self-confidence developed, motivation towards academic achievement \nincreased simultaneously. There was considerable variation in the amount and nature of \ntheoretical preparation. The linking of theory to practice was realised only on return to the \nclassroom in the first year. Conversely, self-confidence was quickly eroded by poor preceptor \nattitudes, lack of communication, and feeling undervalued. The threat of the formal \nassessment remained powerfully dominant over creativity and the development of critical \nthinking which consequently hindered the development of self-confidence. \nConclusion \nThis study offers a new understanding of facilitators and barriers to the promotion of selfconfidence \namongst nursing students that has international relevance for undergraduate \neducation. The development of self-confidence needs to be targeted from the \ncommencement of the first year as opposed to nursing students feeling unprepared and \nlacking self-confidence at the point of qualification. The development of an identified learning \noutcome in the design and delivery of undergraduate nursing programmes is recommended \nto demonstrate the importance of this attribute. Secondly, this is required to combat the \ncurrent assumption that self-confidence occurs spontaneously during the undergraduate \nnursing programme. A set of recommendations have been developed to aid the \nenhancement of self-confidence in the educational preparation of nursing students for the \ncomplexities of nursing in the 21st century.