This study had Three main objectives: 1) to identify a group of variables which could clearly discreminate between male teachers who quit smoking and the ones who unsuccessfully attempting to quit smoking, 2) to compare psychological characteristics of the teachers who had different kinds of smoking behaviors, and 3) to compare the motivations in attempting to quit smoking and the smoking cessation behavior of the teachers who unsuccessfully attempted to quit smoking and the ones who did it successfully. Data were collected from 200 secondary school male teachers in Nakonrajsima province. These teachers represented 4 groups of smoking behaviors: 1) non-smokers (G 1) 2) smokers, (G 2)   3) smokers who unsuccessfully attempted to quit smoking (G 3) 4) ex-smokers  (G 4) Each group contained 50 teachers. 
                Eight questionaires were used to measure 1) personal data, 2) attitude toward smoking, 3) daily stress, 4) locus of control, 5) achivement motivation, 6) smoking behaviors, 7) attitude toward smoking cessation, 8) smoking cessation activites. The non-smokers completed the first five questionaires, the smokers completed the first seven questionaires, and the other two groups of subject completed all eight questionaires. The data were analyzed by using the statistecal package SPSSX   with the significant level set at .05. 
                For  the whole group, the results revealed that : 1) the average age at which teachers started trying to smoke was 17 years, 2) the average age at which teachers began smoking habits was 21 years, 3) the average age at which teachers tried to stop smoking first time was 28 years, and 4) the average age at which the teachers successfully quit smoking was 33 years. 
                Sixteen percentage of the non-smokers group (G 1) had never tried to smoke and the remaining eighty-four percentage had tried to smoke but never again in any situation. Sixty percentage of the smokers group (G 2) wanted to quit smoking but had never tried to do so, twenty-four percentage did not want to quit smoking, and the remaining sixteen percentage did not respond to this quesion. Sixty-four percentage of the third group (G 3) had quit smoking but later resume smoking again. The range of the times of attempting to quit smoking was 1-9 and the most was 2. Each time, most of them could stop smoking for one month. 
               From the eight questionaires used, the questionaires number 1-7 contained 22 perdictive variables. These twenty-two variables were found to be able to discriminate clearly between the ex-smokers (G 3)  and the smokers who unsuccessfully attempting to quit smoking (G 4). And the perdictive index of the group membership was 73%. Of those 22 variables, five variable were found to be the most important in discriminating the two groups, with the perdictive index of 70 %. These five variables were two types of smoking behavior getting used to having cigarette in hand and having stimulate by cigarette, the number of smokers at home, daily stress in economic and personal aspects, and attitude toward smoking cessation. The perdicted standard function was as follows: 
D = .3703 V 28 - .5705 V 29 + .4795 V 2 + .4331 V 25 - .4893 V 34 
               The resulting significant differences in psychological characteristics of the teachers  in the four groups, using one-way ANOVA, were : the non-smokers group  (G 1 ) had more positive attitude toward smoking  concerning 
health, socia-interaction, and daily life, than the smokers group (G 2 ). The smokers who unsuccessfully attempting to quit smoking group (G 3)  had more positive attitude toward smoking (only the attitude concerning health) and more positive attitude toward smoking cessation than the smoker group (G 2). The ex-smokers group (G 4) had more positive attitude toward smoking (only the attitude concerning daily life) and more positive attitude toward smoking cessation 
than the smokers who unsuccessfully attempting to quit smoking group (G 3). The ex-smokers group (G 4 ) had less daily stress in economie and personal aspects than the smokers who unsucessfully attempting to quit smoking group (G 3). Furthermore, it was found that the ex-smokers group (G 4) had more positive attitude toward smoking concerning social-interaction and higher level of achivement motivation but had a smaller number of smokers at home and less daily stress in job than the smokers who unsuccessfully attempting to quit smoking group (G 3). 
                Results from the x2- test revealed that, among the four aspects of motivation to quit smoking, the ex-smokers group (G 4) refered to health aspect more often than the other three the unsuccessfully attempting to quit smoking group approximatly equally referred to the four aspect of motivation. 
                Fourteen smoking cessation actvities were found in this study. Among these activities, five were found to be used substantilly. They were: 1) not buying any cigarettes, 2) controlling oneself not to smoke in some specific situation first and then generalized to other situation, 3) reminding oneself of danger cigarette smoking, 4) keeping a promise to oneself not to smoke, and 5) using something else such as gums and candises to substitute cigarettes. The successful smoking cessation activities reported by; the ex-smokers group (G 4) was keeping a promise to oneself not to smoke, and the smokers who unsuccessfully quit smoking group (G 3) were reduced their smoking, using something else to substitute cigarettes and controlling oneself not to smoke in some specific situation first and then generatized to other situation.