We are currently crunching data from a number of interesting sources. This includes a brand new meta analysis of formal youth mentoring programs, a second look at a four-wave study of adolescents and their mentors (Add Health), and a series of analyses of US Census and Gallup poll data.
Raposa, E.B., Dietz, N., & Rhodes, J.E. (2017). Trends in Volunteer Mentoring in the United States: Analysis of a Decade of Census Survey Data. American Journal of Community Psychology, 1, 1-12. [PDF]