The study aims to assess the role of social support, sociocultural adjustment, and other social and demographic factors in international students' mental health. In total, 193 international first-year students studying Health and Technology Sciences in Lithuania filled out a self-report questionnaire. The study revealed that overall 59% of international students had symptoms of depression and 36%—of anxiety. Students' well-being was sufficient in 56% of the cases. The regression analyses were conducted to test the role of sociocultural adjustment, social support, English reading skills, and the study field for mental health and well-being. The multivariate regression model revealed that sociocultural adjustment is a stronger predictor compared to social support for depressiveness (βs = 0.42), anxiety (βs = 0.30), psychosomatic symptoms (βs = − 0.24), and subjective health (βs = 0.16), though social support was a stronger independent predictor for well-being (βs = 0.37). Moreover, sociocultural adjustment and social support were stronger predictors than gender, while English reading skills and study field were non-significant indicators.