A corpus of c. 250 h of recorded young children-adult interactions in US and UK households, shows that children can be instructed to alter their conduct by three syntactic formats that provide alternatives: an imperative, or a modal declarative, plus a consequential alternative to non-compliance, or an interrogative requiring a preference. Formatted syntactically as or-alternatives, these can execute the actions both of warning and threatening. But they make a ‘bad’ course of action contiguous to the child's turn. Adults are argued to choose this format because the interactional predilection for contiguity makes the negative alternative the more notable one. This implies that adults ascribe to children the skill to grasp the breach of preference organisation for deontic effect.