There is a widespread belief that youth mentoring contributes to students' holistic competency development, but research has not yet provided enough clarity on how exactly this contribution is made possible. To address this gap, in the current study we explore different mentoring strategies and their impacts on mentees' holistic competency development in an extracurricular mentoring programme for secondary school students in Hong Kong. Informed by both mentors' interviews and mentees' written/video reflections, we present three scenarios illustrative of the connection between mentoring strategies and impacts. Through detailed vignettes, we offer a productive and situated approach to understand the extent to which certain mentoring strategies are more likely to contribute to particular holistic competency outcomes.