Children continue to use technology at an increasing rate, more and more of which require authentication via usernames and passwords.We seek to understand how children ages 5-11 years old create and use their credentials. We investigate children’s username and password understanding and practices from the perspective of both children and adults within the context of three security categories: credential composition (e.g. length of password), performance (e.g. time to enter), and credential mechanisms (e.g; a pattern or characters). We conducted a semi-structured interview with 22 children and an online survey with 33 adult participants (parents and teachers) to determine their practices and involvement in facilitating authentication for their children. Our study illustrates how children have a limited understanding of authentication, and that there are differences between children’s and adult’s understanding of good authentication and security practices, and what they actually do.