In six experiments I investigated children’s handling of intensional contexts. The results were described in terms of a developmental extension of Fauconnier’s mental spaces account of meaning representation. Implications for children’s mentalistic development were explored. In chapter 1 I considered the “referential opacity” raised by the representational nature of the mind. I interpreted the findings of Russell (1987) as evidence for a developmental dissociation between handling of intensional contexts - due to the partial nature of representations - and “intentional” referential problems - due to representations being outdated or hypothetical. In experiments 1-3 I demonstrated this dissociation explicitly, and showed that it extended to non-linguistic intensional contexts. Experiments 4 &5 showed correlations between children’s handling of intensional contexts and linguistic ambiguity, which I explained by their common requirement that representational content be held as partial. Experiment 6 showed that children’s handling of intensional questions (and mentalistic explanations) improved after observing incorrect action on the basis of partial knowledge. This effect of supporting context was short-lived, suggesting that it supported on-line activity not question comprehension. After earlier success with out-dated and hypothetical representations, children’s handling of partial representations at 6-7 years explains their concurrent late success with intensional contexts and linguistic ambiguity, and constitutes a qualitative change in their representational abilities.