Siblings are the longest relationship many people have in their lives, yet are often overlooked in research. Transracial adoptees, who may struggle with forming a sense of racial identity and experiencing low self-esteem, may benefit from the presence of a sibling of color. The research questions posed by this study are 1) What is the independent effect of having a sibling of color for transracial adolescent adoptees' racial identity and self-esteem? 2) Does having a sibling of color moderate the well-established relationship between parental racial socialization and outcomes of racial identity and self-esteem in transracial adoptees? Results of the present study indicated that having a sibling of color was negatively associated with a transracial adolescent adoptees’ self-esteem and having a sibling of color moderated the relationship between racial socialization and self-esteem. Higher racial socialization was associated with lower self-esteem for adoptees with no sibling of color.