Abstract: This thesis used a Heideggerian Hermeneutic approach to explore the experiences of registered nurses who act as preceptors to undergraduate student nurses. The researcher interviewed fifteen volunteer registered nurses twice as preceptors to investigate their experience. The data generated was audio-taped and analysed. Four dominant themes emerged. The first, 'Becoming attuned – the call', related to registered nurses responding to the call to be preceptors to students in their clinical placement. The second, “The emerging identity of being-as preceptor: keeping the student in mind”, related to preceptors cultivating their own identity as preceptors as they worked with students in the world of nursing practice. The third, 'Assessing where the student is at: the preceptor and preceptee working and growing together', related to a constant evaluation by preceptors of students' knowledge, readiness to learn, and the provision of learning opportunities. The fourth, 'Preceptors as builders of nursing practice through teaching reality nursing', facilitated the preceptee's experience of the real world of nursing practice. An overall constitutive theme: 'Preceptors as the safeguarders of the practices of nursing', emerged as the essence of the experience.