This research investigated children's and adults' understanding of the mind by assessing beliefs about the temporal features of mental states. English‐speaking North American participants, varying in socioeconomic status (Study 1: N = 50 adults; Study 2: N = 112, 8‐ to 10‐year‐olds and adults; and Study 3: N = 116, 5‐ to 7‐year‐olds and adults; tested 2017–2022), estimated the duration (seconds to a lifetime) of emotions, desires (wanting), preferences (liking), and control trials (e.g., napping and having eyes). Participants were 56% female and 44% male; 32% Asian, 1% Black, 13% Hispanic/Latino, 38% White (non‐Hispanic/Latino), and 16% multiracial or another race/ethnicity. Children and adults judged that preferences last longer than emotions and desires, with age differences in distinguishing specific emotions by duration (). By 5 to 7 years, ideas about the mind include consideration of time.