This chapter examines the effects of two risk factors (economic disadvantage and family non-intactness) and two protective factors (positive youth development and family functioning) on substance abuse among Chinese adolescents in Hong Kong. Based on four waves of data collected from Secondary 1 to Secondary 4 students in a longitudinal study (3328 students at Secondary 1), individual growth curve models demonstrated a growing trend of adolescents engaging in substance abuse across time. Gender, age, and family intactness were significantly related to the initial status of adolescent substance abuse, while economic disadvantage and family intactness were significantly related to the growth trajectory of substance abuse, with adolescents from poor and non-intact families having a higher risk of engaging in substance abuse. While positive youth development and family functioning at Wave 4 predicted substance abuse in Wave 4, positive youth development and family functioning at Wave 1 only predicted smoking but not overall substance abuse at Wave 4.