BACKGROUND : Activity-based intervention has been defined as a child-directed, transactional approach that uses logically occurring antecedents and consequences to develop functional and generative skills by embedding intervention of children’s individual goals and objectives in routine, planned or child-initiated activities. In this approach, clear goals and objectives that are functional and embedded in a play activities or routines are developed. The teacher mediates the child’s environment to facilitate learning with the child directing the teacher on the pace, duration spent on the objective. Learning and development in this framework occur through both a carefully planned environment and adult facilitation. Progress made by a child using this approach focuses on observational data that describe if the child is able to respond in functional and generative ways. While activity-based interventions are usually provided for a group of children, progress is measured by describing individual children’s responses. Individual variations in the children’s progress, despite exposure to the same interventions are an area that is seldom discussed. This article aims to explore the niche concept and its application to explaining this variation between individuals. METHODS : Four children participated in this single-subject, multiple-probe study across four participants. A 3-week long activity-based aided language stimulation programme was developed. The effect of the programme was determined by describing the individual participants understanding of the 24 targeted vocabulary items. RESULTS : The results of the activity-based language programme are presented and the variability among the participants is discussed using the niche concept. The role of the niche concept in individual development is described and the implications thereof are discussed. CONCLUSIONS : Finally, activity-based intervention research is placed in a systems perspective and possible outcome measures of this intervention are discussed from a multidimensional ecological perspective.