This study discusses internal communication within industrial clusters. The basic research question is whether there is a correspondence between the success of a cluster and the communication practices of its management. Our aim was to explore these practices both between the management organization of a cluster and the clustered firms and also among the cluster members themselves. After a thorough literature review of cluster communication, qualitative approach was applied using case studies and 28 interviews in three distinctive clusters in Southwest Hungary. Two of the three clusters consider themselves successful, whilst one cluster sees itself less effective. In the two successful ones, cluster managements are able to manage communication effectively and ensure that communication supports their goals and the implementation of their strategies. In these cases, communication management organization planned and established all dimensions of the communication consciously: channels, content, frequency, way and style of communication, all of which have an impact on trust. The research is linked to corporate communication theories, social identity theory, psychology and management. The paper fills a gap in the research of internal cluster communication. The findings also have useful implications regarding the practice of cluster management and communication. [ABSTRACT FROM AUTHOR]