Part 1 of this 2-paper series identified a wide and deep network of context, generative mechanisms and outcomes responsible for psychosocial development in a performance basketball club. In this – part 2 – study, the stakeholder’s programme theories were tested during a full-season ethnography of the same club. The findings confirm the highly individualised nature of each young person’s journey. Methodologically, immersion in the day-to-day environment generated a fine-grain analysis of the processes involved, including: i) sustained attentional focus; ii) structured and unstructured skill building activities; iii) deliberate and incidental support; and iv) feelings indicating personal growth. Personal development in and through sport is thus shown to be conditional, multi-faceted, time-sensitive and idiosyncratic. The findings of this two-part study are considered to propose a model of psychosocial development in and through sport. This heuristic tool is presented to support sport psychologists, coaches, club administrators and parents to deliberately create and optimise developmental environments.