We investigated the causal responsibility attributions of adults and children to mechanical devices in the framework of the criticality-pivotality model. It establishes that, to assign responsibility, people consider how important a target is to reaching a positive outcome (criticality) and how much the target contributed to the actual outcome (pivotality). We also tested theoretical predictions about relations between the development of counterfactual thinking and assessments of pivotality. In Experiment 1, we replicated previous findings in adults using our task. In Experiment (...) 2, we administered this task and a brief counterfactual reasoning questionnaire to children aged between 8 and 13 years. Results showed that children also considered both criticality and pivotality when they attributed responsibility. However, older children were more sensitive than younger ones to pivotality. Also, we found a positive correlation between children’s pivotality judgements and a measure of counterfactual thinking. Results are discussed regarding the model’s relation to counterfactual thinking. (shrink)