Background:
Few studies have compared the psychosocial risk profiles for youth who begin using tobacco with e-cigarettes only, cigarettes only, or both of these products.

Methods:
More than 40 known psychosocial risk factors for youth tobacco use, including intra-personal (e.g., sensation seeking), inter-personal (e.g., peer influence), and environmental (e.g., tobacco marketing) factors were compared between those who started with e-cigarettes only (n=156, N=14550), cigarettes only (n=59, N=7325), or both of these products (n=35, N=3510). Psychosocial risk factors were measured at baseline (2014-15) and tobacco use behaviors at 6, 12, and 18 month follow-ups (2015-16) in a population-based sample (n) of 3,116 students in 4 large urban areas of Texas that generalizes back to 353,552 students (N) who were in the 6^th, 8^th, and 10^th grades and had never used tobacco at baseline.

Results:
Youth who started with cigarettes only or both, compared to youth who started with e-cigarettes only, were more likely to have a family member that used cigarettes or e-cigarettes (p< 0.01) and be past 30-day marijuana users (p=0.01) at baseline. Youth who started with e-cigarettes only, compared with the others, reported a higher positive affect (p=0.01) and lower negative affect at baseline (p=0.01) and were more likely to have positive outcome expectations about tobacco use (e.g., it helps me concentrate; p=0.05) and be past 30-day alcohol users (p=0.05) at baseline. Youth who started with both products, compared to one exclusively, were more likely to have engaged with tobacco-related content on digital media (e.g., posted pictures, blogged) (p< 0.05) and less likely to report seeing displays for cigarettes at retail point-of-sale (p< 0.01) at baseline. No other differences in known risk factors (e.g., sensation seeking) were observed.

Conclusions:
Psychosocial risk profiles do vary significantly by starter tobacco products. Implications for intervention will be discussed.