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i. To develop an automated measurement technique for the assessment of both the form and intensity of physical activity undertaken by children during play. ii. To profile the varying activity across a cohort of children using a multivariate analysis of their movement patterns.Ankle-worn accelerometers were used to record 40-minutes of activity during a school recess, for 24 children over 5 consecutive days. Activity events of 1.1 s duration were identified within the acceleration time trace and compared to a reference motif, consisting of a single walking stride acceleration trace, obtained on a treadmill operating at a speed of 4 km h-1. Dynamic time warping (DTW) of motif and activity events provided metrics of comparative movement duration and intensity, which formed the data set for multivariate mapping of the cohort activity using a principal component analysis (PCA).The 2-D PCA plot provided clear differentiation of children displaying diverse activity profiles and clustering of those with similar movement patterns. The 1st component of the PCA correlated to the integrated intensity of movement over the 40 min. period whilst the 2nd component informed on the temporal phasing of activity.By defining movement events and then quantifying them by reference to a motion-standard, meaningful assessment of highly varied activity within free play can be obtained. This allows detailed profiling of individual children’s activity and provides an insight on social aspects of play through identification of matched activity time profiles for children participating in conjoined play.