This study sets out to determine how French children's comprehension of promises and their corresponding metapragmatic knowledge is affected by (non-)satisfaction of the preparatory and/or the sincerity condition, and by the linguistic form of the statement. Interpreted in the light of functionalist and interactionist theories of development, the results show that: by the age of 3, both conditions are used to comprehend promises; children's metapragmatic knowledge depends on the satisfaction of the conditions and changes with age; the statement's linguistic form has little effect on promise understanding.