Integrating electronic referral systems into clinical practices may increase use of web-accessible tobacco interventions. We report on our feasibility evaluation of using theory-driven implementation science techniques to translate an e-referral system (ReferASmoker.org) into the workflow of 137 community-based medical and dental practices, including system use, patient registration, implementation costs, and lessons learned. After 6 months, 2,376 smokers were e-referred (medical, 1,625; dental, 751). Eighty-six percent of the medical practices [75/87, mean referral = 18.7 (SD = 17.9), range 0-105] and dental practices [43/50, mean referral = 15.0 (SD = 10.5), range 0-38] had e-referred. Of those smokers e-referred, 25.3 registered [mean smoker registration rate-medical 4.9 (SD = 7.6, range 0-59), dental 3.6 (SD = 3.0, range 0-10)]. Estimated mean implementation costs are medical practices, US$429.00 (SD = 85.3); and dental practices, US$238.75 (SD = 13.6). High performing practices reported specific strategies to integrate ReferASmoker.org; low performers reported lack of smokers and patient disinterest in the study. Thus, a majority of practices e-referred and 25.3 % of referred smokers registered demonstrating e-referral feasibility. However, further examination of the identified implementation barriers is important as of the estimated 90,000 to 140,000 smokers seen in the 87 medical practices in 6 months, only 1,625 were e-referred.