A Cluster DEVELOPMENT Agent (CDA) according to his specific roles and tasks in different stages of cluster DEVELOPMENT process – which includes 5 different stages based on UNIDO cluster DEVELOPMENT model, namely: cluster selection, CDA selection, diagnostic study, vision building and action planning, implementation and finally monitoring and evaluation – requires a different set of COMPETENCIES in each stage. This study examines COMPETENCIES which are of the most important and also critical prerequisites for the success of the cluster DEVELOPMENT project. Accordingly, investigating the trustworthiness of the CDA from the perspective of cluster stakeholders, as well as his ability to create and enhance the level of trust between cluster members, is the main subject of this research. In fact, the main goal of this research is identifying COMPETENCIES that increase the trustworthiness of the CDA and develop the level of trust within the cluster. In this qualitative study with a narrative approach, using profound and semi-structured interviews with 16 cluster developers and six cluster stakeholders, the COMPETENCIES were identified and determined. These COMPETENCIES include the ability to: sensitizing stakeholders, create partnerships, persuasion, and finally creating added value.