Background: In recently ruling on the over-the-counter status of the emergency contraceptive, Plan B, the FDA questioned whether adolescents could adequately self-select and self-medicate, and more generally how increased Plan B availability would affect adolescent sexual behavior. The FDA objected to extrapolating evidence from older to younger adolescents, arguing that developmental differences may cause younger adolescents to exhibit more impulsive behavior due to their cognitive constraints. We suggest an approach to this class of problems, reflecting analytical and empirical methods grounded in behavioral decision research. Methods: We conducted 30 in-depth individual interviews and a follow-up survey with 125 adolescent females to examine adolescents' views about Plan B and the effects of its availability on their sexual decision-making. Results: We found no systematic differences between younger (<16) and older teens in the interviews and only four in the surveys: Younger teens were (a) less likely to know about Plan B, (b) less likely to cite pleasure as reason to have sex, (c) more likely to cite physical discomfort as reason to avoid sex, and (d) less likely to think that greater availability would not affect their peers unprotected sex (an expectation that did not apply to their own behavior). Conclusions: We conclude that although FDA expressed concern about younger teens substituting Plan B for their primary form of contraception, our results find their decision making capability in this context to be much like that of older teens. The few differences between them suggest that younger teens might actually be less impulsive and less likely to rely on Plan B. More generally, we conclude that such a behavioral decision research approach to such regulatory choices can make these rulings more predictable and transparent.