Organizational capacity is a concept that has garnered increased attention from the public and nonprofit management literature in recent years. Capacity, broadly defined as the ability of an organization to fulfill its goals, has been of particular focus of scholars interested in understanding the variables that impact organizational performance. Despite the increased focus on organizational capacity in the literature, the concept remains vague. Given the fuzziness of the concept of capacity, there is much opportunity to contribute to the field's knowledge and measurement of the concept. This dissertation adds depth to the capacity literature in public and nonprofit management by identifying, describing and measuring the different dimensions of capacity relevant to local social service delivery organizations. Utilizing a two-phase sequential mixed method design including both interview and survey data, the findings suggest that organizational capacity consists of a number organizational resources and capabilities that impact the functioning of the internal organization as well as its relationships with other relevant organizations and external stakeholders. In particular, six dimensions of capacity were identified: human resource, financial resource, information technology, knowledge, stakeholder commitment, and collaborative. The survey results indicate that the six dimensions are connected to the theoretical construct of organizational capacity. However, results from the discriminant validity tests of the six subscales are mixed. This finding implies that these dimensions represent broad constructs that impact the other dimensions directly. This finding also highlights the challenge of defining and measuring discreetly the specific dimensions of capacity. Future research should examine these discrepancies in order to further disentangle capacity as a theoretical construct.