Although it is one of the core cultural values of Asian American families and an influential determinant of youth development, familism remains under-studied among Asian Americans and, despite crucial within-group heterogeneity, lacks subgroup specificity. This study describes the ways in which two major Asian American subgroups of youth, i.e., Filipino Americans and Korean Americans, maintain traditional familism. Specifically, this study constructed six self-report subscales of familism utilizing underused and new survey items and tested their psychometric properties. Using data collected from Filipino American (n=150) and Korean American (n=188) adolescents living in a Midwest metropolitan area, the measures were examined for validity and reliability for each group and, when appropriate, for measurement invariance across the groups. The main findings are that the finalized scales demonstrated solid reliability and validity (e.g., content and construct) in each group and some invariance and that core traditions, in the form of familism values and behaviors, persevere among second-generation Asian Americans, although familism was more evident among Filipino American youth than in Korean American youth. In both groups, subdomains of familism were not as discrete as found among their parents, who were predominantly foreign-born first-generation immigrants. The finalized familism scales were associated differently with several correlates including acculturation variables and youth outcomes. The findings are discussed with a call for further empirical research of diverse ethnic groups and immigrant generations to more accurately account for how family process interacts with cultural origin and acculturation.