There is a long-standing call for robust empirical evidence that a residential experience of outdoor adventure activities (OAA) is beneficial for the personal and social development (PSD) of young people. This call reflects the fact that consistently strong anecdotal and qualitative evidence of positive benefit is not mirrored in quantitative measures. To date, statistically significant measures of benefit, almost entirely made outside Scotland, range from negative to medium positive effect sizes. This quantitative research measures the benefit of a residential week of introductory OAA for the PSD of upper primary school children, with the overarching aim of contributing to the argument for full funding of a “residential” for every Scottish school pupil. In the absence of suitable questionnaires, a questionnaire tailored to the project was created and tested for validity and reliability. Despite poor reliability, but encouraged by the repeatability of the distribution of pupils’ mean scores across administrations, the research was continued. Scores from over 300 pupils yielded a small, statistically significant improvement in their perception of their PSD skills from immediately before to immediately after their “residential”, but then a large decline measured two-three months later. Underlying this trend, low-scoring pupils perceived greater benefit and retained this into the delayed test, girls demonstrated a more positive view of their skills than boys, and all pupils had greater belief in their social competence than in their confidence. Socio-economic data clearly supported the presence of a school effect, there was some evidence of a euphoria effect around the time of the “residentials”, and some evidence of improved understanding of the concepts embodied in the questionnaire over successive tests. Regarding the implications of these results for research methodology, it is suggested that inconsistency in quantitative measures of benefit relates, in part, to the presence of numerous variables and survey effects that are often poorly constrained. For teachers, it is suggested that the observed loss of benefit 2-3 months later might be overcome if the experience is better integrated into the curriculum. For education policy makers and funders, the implication is that only if the experience is available free of charge to all pupils will it be fully integrated and its full benefit realised. Outdoor centre managers are encouraged to maintain quantitative records of pupils’ and teachers’ feedback on benefit to strengthen the case for full funding.