Introduction: Social capital is the result of interactions among humans, organizations and institutions based on trust, empathy and norms that facilitated by social participation and cooperation for resulting to common interest. Social capital is the sum of resources that accrue to an individual or a group by possessing a durable network of more or less institutionalized relationships of mutual acquaintance and recognition. This construct is discussed and analyzed in different macro, middle and micro levels. Therefore, it has found increasing use in social sciences as well as in other fields such as health, management, economics and politics. Actually, social capital has a numerous definition and division in terms of scientist and scientific perspectives and for this reason this concept has faced with measuring problems. So, it is necessary to constructed and validated scale for social capital. In the most studies the separate forms of social capital has been neglected. The lack of proper scale that measure both forms of bonding and bridging social capital is one of the reason for this situation. So, the main purpose of this research is building and validating scale for the social capital. This scale can help researcher to conducting and measuring this concept without any problem.  
 
Method: The research method is correlation. In this research 28 items of social capital project and 12 items of bridging (SAM scale) are analyzed. The sample population was 415 people 189 (45.5%) female and 226 (54.5%)  male in 18-70 age range with multi-stage cluster sampling method in three areas of Tehran based on low, middle and high economic-social status. In terms of education respondents were Deploma to Ph.D level. For evaluating the suitability of data for factor analysis Bartlett's test of sphericity and the Kaiser-Meyer Olkin scale was used. The result of the Kaiser-Meyer Olkin scale (KMO = 0.791) shows the adequacy of sampling. The exploratory factor analysis were estimated with varimax rotation based on the construct validity and reliability by Cronbach's alpha coefficient (internal consistency).

 Findings: In the total of 40 items, finally, 20 items remained that compose the "social capital questionnaire" and measure this construct in bonding and bridging social capital. Three structure of scale factors are  related to  bonding social capital (empathy and belonging, trust, partnership) and two structure of scale factors are related to bridging social capital (different interests, different lifestyle). So, we make a scale for social capital that measure both of Bonding and Bridging social capital together. Their structural factor consist of 5 dimensions (empathy and attachment, different interests, different lifestyle, trust, participation) that explain 58% of social capital variation. Meanwhile, the scale has a high reliability (α=0/825).
 
Discussion: This scale made a suitable measure for recognition of social capital forms in future research among different groups and also for studying reasons and results of them. It is suggested that researchers use this scale in their studies for describing the state of bonding and bridging social capital in different populations and to identify interventions for promoting of social capital forms. It is recommended to be used as a criterion validity in future studies and in further research. It is important to addressed and validate this scale in other cities and certain groups such as the disabled, the addicts, and students.