Purpose-The purpose of this paper is to study the process in which dynamic capabilities renewed operational capabilities to sustain competitive advantage in management consulting firms of Iran during a period of drastic environmental changes. Design/methodology/approach-Using a grounded theory building approach, comparative longitudinal case analyses were conducted in consultancies of Iran. The research was based on a deep study of documents, observations and interviews with managers and employees of 14 consulting firms. Findings-It was found that during a period of environmental changes there was a relationship between dynamic capabilities and competitive advantage, but this relationship was mediated by the role of marketing and technological capabilities of a firm. It was also found that trust-building capabilities of the consulting firms moderate the relationship between dynamic and operational capabilities. The research explores homogeneity and heterogeneity of dynamic capabilities among consultancies too. Originality/value-This research shows that under changing environmental conditions, dynamic capabilities of consultancies can become a source of competitive advantage. Moreover, it discusses whether dynamic capabilities are idiosyncratic or are best practices. It also explains the role of trust-building capabilities of consulting firms in moderating the relationship between dynamic and operational capabilities in the particular environment of Iran.