Although physicians' brief advice against smoking is effective in helping smokers to stop, very little is known about the process of counseling smokers. We describe the development of a coding system for describing smokers' motivation to stop smoking as judged by their behaviour when discussing smoking with their family physician. We analysed video-recordings of consultations between 47 self-reported smokers and 29 family physicians where smoking was discussed. By a process of observing recordings, reading transcripts and discussion, we developed a coding system for describing smokers' levels of motivation to stop smoking. This consists of four behaviours thought to indicate "readiness" (higher motivation to stop) and four "resistance" (lower motivation to stop). Interobserver reliability between two observers was good (Kappa = 0.71 for readiness, 0.73 for resistance behaviours). We discuss the relevance of our descriptions for clinicians and the possibility of developing this work further to enable systematic research into doctor-patient interactions where smokers are counseled to stop.