Using data from the Health Behaviour in School-aged Children (HBSC) Study 2005/2006, and World Health Organization (WHO), this study examined the relationship between girls' informal social capital and female suicide rates in adolescence and young adulthood in 30 European and North American countries. Regression analyses using normal, robust and bias-corrected confidence intervals were used for this purpose. Informal social capital (involvement with friends after school) among 15 year-old girls explained,9% of the total variation in the young female suicide rate. This effect was of approximately the same magnitude as that of the corresponding male suicide rate. Although the findings of this study provide support for the common notion that female suicide can be understood in relation to male suicide, the association we observed between female informal social capital in adolescence and early adult female suicide highlights the need for more female-specific studies on suicide.