Objective: To study whether demographic and smoking-related characteristics are associated with participation (reach) in a smoking cessation trial and subsequent use (uptake) of two specific smoking interventions (Internet-based program and proactive telephone counseling). Methods: We used data from a four-arm randomized smoking cessation trial (2011). Participants (n= 1,809) were recruited among 9,924 smokers who previously participated in two health surveys in Denmark (2007-2008 and 2010). Interventions were as follows: (1) an Internet-based smoking cessation program, (2) proactive telephone counseling, (3) reactive telephone counseling and (4) a self-help booklet. Results: Reach (defined as the proportion accepting to participate in the trial of those invited) was highest among persons aged 40-59. years, women, heavy smokers and persons with long education. Among trial participants, uptake (defined as any use of the specific intervention at 1-month follow-up) was 69% for the Internet-based program, 74% and 9% for proactive and reactive telephone counseling, respectively, and 84% for the self-help booklet. Young age was associated with the uptake of the Internet-based program, and short education was associated with using proactive telephone counseling. Conclusions: Internet-based interventions and proactive telephone counseling appeal to different age and educational groups. Further, offering similar intervention content by a proactive and a reactive approach can be associated with different intervention uptake.