Osteoarthritis is a recently major public health problem among increase aging population. This study was aimed to examine osteoarthritis preventive behavior among aging population in Thammasat University Hospital Aging Club, Patumtanee Province and to find the way to promote such behavior. Health Belief Model and Self Efficacy Theory were applied to conceptual frame work for conducting Health Education Program including a lecture with videotape, a demonstration and skill training, a home visiting discussion. A quasi-experimental study design using simple random sampling technique was employed to obtain a sample of 2 districts, one for the experimental district and the other for the comparison district, while a purposive sampling technique was employed to obtain a sample of 76 agings of Thammasat University Hospital Aging Club Members. The 40 agings from experimental district were assigned to be an experimental group and 36 agings from comparison district as a comparison group. Only experimental group were participated in Health Education Program. Data were collected by questionnaire interviewing, weighing and measuring of quadriceps muscle strength before and after the six-week experiment. Descriptive statistics, paired sample t-test, students t-test, Pearson product moment correlation coefficient, chi-square test,Fisher exact test and Kendalls tau b were used to determine the significant factors and their relationship. The results showed that there were statistically significant differences variables namely perception, expectation,osteoarthritis preventive behavior, the weight and quadriceps muscle strength between the experimental group and the comparison group. In addition, it was found that perception and expectation were significantly correlated with osteoarthritis preventive behavior. However, sex, education and osteoarthritis history were not related to perception and expectation of osteoarthritis but income The result of this study indicated that the Education Program for aging people based on Health Belief Model and Self Efficacy Theory encouraged their preventive behavior on Osteoarthritis to the point that they could control body weight and increase thigh muscle strength. As a result, this Health Education Program is also recommended among other aging groups.