Background: Coaches developing young talent in team sports must maximise practice and learning of essential game skills and accurately and continuously assess the performance and potential of each player. Relative age effects highlight an erroneous process of initial and on-going player assessment, based largely on subjective opinions of game performance. A more objective assessment of each player's progress by measuring essential skills during practice is warranted to guide and improve coaching and assessment of talented children. Purpose: To measure the effects of the coaching intervention on performance and learning during a group technical practice. A second purpose was to repeatedly measure each player's passing, first touch and an awareness response and to measure the reliability of peer assessment as an immediate source of objective feedback. Setting: Weekly coaching sessions at an English professional soccer club academy. A total of 22 practices occurred during the second half of a soccer season. Participants: Academy boys aged 10-12 years, with five players participating throughout the study. The coach was a European "A" licence holder and an experienced physical education teacher. Intervention: The coach and players defined the practice requirements and how to perform each skill successfully. Players were taught to observe, assess and record the performance of their peers. After the practice, players charted their objective scores and bonus game play was awarded based on self-set goal attainment. Research design: A single-subject, multiple-baseline experiment was used to assess the effects of the intervention on performance of the three skills and the reliability of the performance measures. The design and intervention enabled the repeated measurement of all players' performance and learning during each phase and condition of the experiment. Data collection and analysis: Baseline data were collected from video recording of practice and intervention data were collected from recording and live by a player and the coach. Percent correct scores for each skill were plotted on graphs for visual analysis. Agreements between live and primary video data were calculated to evaluate the reliability of peer-assessed scores. Findings: The intervention was shown to improve the level and consistency of performance in all five participants, which, for most players and skills, was maintained when the intervention was removed. Players were willing and able to reliably assess their peers and collect objective data on each player's performance. They enjoyed receiving and charting their scores and reported a greater confidence in these skills in competitive situations. Conclusions: The findings suggest this formal accountability, feedback and reinforcement procedure provides a promising method to maximise practice and learning and accurately assess the progress of talented youth soccer players. Further research is recommended to examine the congruent validity of performance measures from more complex learning tasks to discriminate talent and tackle relative age effects. Implications for future talent development coaching and coach education include the potential for repeatable and measurable systems (a technology) to track performance and learning during coaching-practice to help develop and determine the most able children. (Contains 7 figures.)