Findings from two studies investigating the relationships between two types of family-centred practices (relational and participatory) and parent involvement in early childhood intervention are described. We tested the hypothesis that participatory practices would be more strongly related to parent involvement compared to relational practices because the former and not the later emphasise active parent participation in obtaining child, parent, and family resources and supports. We also determined if the pattern of results were the same or different in the two studies. Both studies were conducted in Spain in nine early childhood intervention programmes working with young children with identified disabilities or developmental delays and their parents. Participants completed a family-centred practices scale and parent involvement scale as part of their participation in the studies. Results from different kinds of statistical and effect size analyses provided converging evidence that participatory family-centred practices were a more robust predictor of parent involvement in early childhood intervention compared to relational family-centred practices. Implications for professional development to promote early childhood intervention practitioners’ understanding and use of participatory practices to improve parent involvement in their children’s intervention are described.