In accordance with ethical principles and standards, researchers conducting studies with children are expected to seek assent and respect their dissent from participation. Little attention has been given to assent and dissent in research with toddlers, who have limited cognitive and emotional capabilities. We discuss research with toddlers in the context of assent and dissent and propose guidelines to ensure that research with toddlers still adheres to ethical principles. These guidelines include designing engaging studies, monitoring refusal and distress, and partnering (...) with parents. Research with toddlers requires flexibility and creativity to respect toddlers in the context of their developmental capabilities. (shrink)