Two studies, with 102 nonmaltreated 3- to 6-year-old children and 96 maltreated 4- to 7-year-old children, examined children’s understanding of the relative strengths of “I promise,” “I will,” “I might,” and “I won’t,” to determine the most age-appropriate means of eliciting a promise to tell the truth from child witnesses. Children played a game in which they chose which of 2 boxes would contain a toy after hearing story characters make conflicting statements about their intent to place a toy in each box (e.g., one character said “I will put a toy in my box” and the other character said “I might put a toy in my box”). Children understood “will” at a younger age than “promise.”  Nonmaltreated children understood that “will” is stronger than “might” by 3 years of age and that “promise” is stronger than “might” by 4 years of age. The youngest nonmaltreated children preferred “will” to “promise,” whereas the oldest nonmaltreated children preferred “promise” to “will.”  Maltreated children exhibited a similar pattern of performance, but with delayed understanding that could be attributed to delays in vocabulary.