Due to significance of effective communications in achieving organization goals, Studying necessary communication competencies are also important. The purpose of this research is developing a model for achieving effective organizational communications based on Intra/Interpersonal Communication Competencies. This research is applied in its objective and descriptive-analytical in its method. The statistical population is a group of academic experts; that 17 peoples using Purposive and snowball sampling were selected as the sample. For collecting data and information literature reviewing and expert opinion used. Also, to assess validity and reliability of data gathering tool, the triangulation method used. To analyze the data and information Interpretive Structural Modeling methods are used. The results of this research led to identification of important dimensions of intrapersonal and interpersonal communication competencies that encourage effective organizational communications and designing their interpretive structural model. Results showed that the components of intrapersonal and interpersonal communication competencies at different levels are inter-effective, and changes in the quality of each component causes changes in quality of other components at same level as well as the next levels. Finally it led to changes in quality of the organizational relationships. After interpreting the model and analyzing its levels, suggestions for progress of Intra/Interpersonal Communication at organizations were presented.