Oral health literacy (OHL) is an interplay of cultural, social and individual factors and plays an effective role in public health promotion. This study aimed to assess OHL and its socioeconomic and demographic determinants among young couples. This analytical cross-sectional study was conducted on 828 adults between 15 to 35 years in 2018 in Zanjan city. Data regarding their OHL were collected by using a 17-item Oral Health Literacy-Adult Questionnaire (OHL-AQ) that was filled out by a combination of self-report and interview. OHL was categorized as adequate, marginal, and inadequate. The effects of age and gender as demographic variables, and floor area per person as a proxy of financial status on OHL were also assessed. Data were analyzed using the linear and multinomial logistic regression models. The mean OHL score was 7.86±3.83 out of 17 in equal number of males and females. Only 21% of the couples had adequate OHL. The socioeconomic, but not demographic variables had significant correlations with the qualitative and quantitative variables of OHL even after controlling for the effect of confounders. A correlation was particularly found between inadequate OHL and years of education [odds ratio:6.00; 95% CI: 3.86-9.28); P<0.001]. Socioeconomic factors had independent correlations with inadequate OHL. Participants with higher levels of education, those living in urban areas, and individuals with better financial status had higher levels of OHL and lower odds of inadequate OHL.