Gross motor development of young children is characterised by inter-individual and intra-individual variability, partly under the influence of child and environmental factors. This can hinder the correct interpretation of the results of tests which map out gross motor development. Repeated measurements of the progress in gross motor development possibly offers a solution for this, but is a burden for both child and parents if they have to travel to a test location each time for this. Therefore, as part of this dissertation, a home video method was developed as a way of registering the motor development of young children via film footage made at home by parents. In this way, longitudinally measured motor developmental trajectories of children born on time were recorded, starting at the age of 3.5 months and ending at the age of 15.5 months. During the same period, data were collected on child and environmental factors, the competitive validity of the home video method was examined and its application by parents was evaluated. The main outcomes of the studies in this thesis are 1) a first impulse of a gross motor growth curve based on normally developing children, in which within the normal variation three groups could be distinguished: early developers, gradual developers, and late bloomers, 2) a validated home video method that has proved applicable for parents in their home situation and can have an added value for both research and practice and 3) insight in factors that can partly explain the variation in gross motor development by means of a systematic literature study and a study into the beliefs of parents concerning the motor development of their child.
