For a long‐term, longitudinal study that used BlackBerry smartphones for passive ambulatory assessment among older adolescents, this study focused on three areas of ethical concern: (1) adolescents’ competence to give assent; (2) understanding of confidentiality, the protection of information, and project goals; and (3) awareness of procedures and benefits, and comfort with the research design. One hundred and seventy‐eight participants were 17 and 18 years old (84 girls). Results suggested that participants freely gave consent and understood most, but not all of the informed consent information. Participants reported a high level of satisfaction. Participants showed less understanding of when their confidentiality would be broken and how data would be protected.