This paper presents an empirical investigation to study the relationship between social capital components, social trust, social cohesion, social participation and social security, and sustainable development in city of Salmas, Iran. The study designs a questionnaire in Likert scale, distributes it among 384 randomly selected people who live in this city. Cronbach alpha has been calculated as 0.92, which is well above the minimum acceptable level. Using regression technique, the study has determined a positive and meaningful relationship between three components of social capital and sustainable development including social cohesion, social participation and social security. However, the study does not confirm the relationship between social trust and sustainable development.