Binary judgement on under-informative utterances (e.g. Some horses jumped over the fence, when all horses did) is the most widely used methodology to test children’s ability to generate implicatures. Accepting under-informative utterances is considered a failure to generate implicatures. We present off-line and reaction time evidence for the Pragmatic Tolerance Hypothesis, according to which some children who accept under-informative utterances are in fact competent with implicature but do not consider pragmatic violations grave enough to reject the critical utterance. Seventy-five Dutch-speaking four to nine-year-olds completed a binary (Experiment A) and a ternary judgement task (Experiment B). Half of the children who accepted an utterance in Experiment A penalised it in Experiment B. Reaction times revealed that these children experienced a slow-down in the critical utterances in Experiment A, suggesting that they detected the pragmatic violation even though they did not reject it. We propose that binary judgement tasks systematically underestimate children’s competence with pragmatics.