Several theoretical approaches have discussed the role of children’s expectations of their parent’s responsiveness in explaining motivation to collaborate in acquiring skills. This study attempted to measure these expectations in 102 toddlers (M age = 26.4 months) through observations of attention-seeking (A-S) behaviors during caregiver’s restricted availability. Child collaboration was coded during skill-learning tasks (imitation and block building), and parent responsiveness was observed during dyadic activities. Different A-S styles emerged, supporting the existence of both positive and negative expectations of responsiveness. A-S quality statistically mediated the link between parent responsiveness and child collaborative outcomes, even after controlling for temperament and mood. This is the first study to show that toddlers’ expectations are a plausible mechanism linking parent responsiveness to child collaboration.