ABSTRACT Ethiopia holds large potential for milk production due to its large livestock population. However, raw milk market participation is low. This study aimed to study determinants of milk market participation decision and volume of milk marketed by smallholder farmers in Dejen district. To achieve these objectives both primary and secondary data were collected from 222 households. Data were analyzed by descriptive statistics, double hurdle econometric model and relative importance index. Double hurdle model estimates probit model in tier one and truncated model in tier two. From the sample dairy farmers, 43.69% were market participants and the remaining 56.31% were non-participants. The results of the study first hurdle (probit) indicated that market distance and family size were statistically significant and negatively influencing the probability of smallholder dairy farmer’s milk market participation decision, while milk production, frequency of vaccination services and dairy cooperative membership were statistically significant and positively influence the probability of market participation decision. In the second hurdle land-holing size, milk production and dairy cooperative membership were statistically significant and positively influence the volume of milk supply. Farmer’s perception towards milk market perception incline positive. Compares with market participation, market participant household’s perception was positive than non- participant. Milk market participation in the study area was low but the small participant supply more than half of the total milk. Therefore, create and increase milk market, improve milk production, increase veterinary service and improve milk price in the study area are important to improve smallholders market participation, volume of milk supply and farmers perception. Key word, Milk, Participation decision, Volume of supply, Double hurdle