Background: Dietary Diversity is an essential element of diet quality. It also indicates the presence of individual and household food diversity and consumption of adequate nutrient. Lactation is one of the most complex and nutritionally demanding phases of the human life cycle. So, assessing the adequacy of dietary diversity and associated factor is important to improve the health and good nutritional status of their children. There was little studies that assessed adequacy of Dietary diversity among lactating mothers in the study area. Objectives: To assess Dietary diversity and associated factors among lactating mothers in Finote Selam Town Amhara Region North West Ethiopia. Methods: Institution based cross sectional study was conducted in Finote Selam Town in January 2020 among 416 lactating mothers. Participants were selected using Systematic sampling techniques and data was collected using structured interviewer administered questionnaire. Results: - A total 416 respondents were interviewed and the magnitude of adequate dietary diversity was 23.1% (95%CI: 19.2, 26.9). On multivariable logistic regression Spouse Education (AOR=1.81 95%Cl: 1.05, 3.11), occupation of mothers (AOR=2.90 95%Cl: 1.65, 5.10), nutrition education during ANC follow up (AOR=2.65 95%Cl: 1.62, 4.32), wealth index (AOR=2.56 95%Cl: 1.41, 4.63) and household food security (AOR= 1.71 95%Cl: 1.03, 2.84) were significantly associated with having adequate dietary diversity among lactating mothers. Conclusion: - Majority of the study participants consumes 3-4 food groups (68%). Occupation of mother, nutrition education during antenatal follow up, Wealth index and food security status were associated with Dietary Diversity of lactating mother. The findings suggest the need for enhancing nutrition education, food security and crop diversification should be implemented by ministry of Health, Agriculture and Education.