The Last Planner System (LPS) of lean construction was developed in order to address prime issues of the construction industry like lack of certainty and workflow variability which are accountable for its poor performance. LPS can be viewed as a social system where project participants come together and plan collaboratively yet previous research related to lean construction has concentrated more on the technical and commercial aspects than on social aspects. Social interactions and dynamics among project participants play a crucial role in improving workflow reliability and coordination during LPS implementation. Thus, this study focuses on developing a causal loop diagram (CLD) to understand and explore the interaction of various social dynamics variables which are effective in improving the LPS implementation in a construction organization. For this, seventeen social dynamics variables were identified from the literature review process and validated by an expert survey. A total of seven causal loops have been prepared and validated for improving the effectiveness of LPS implementation. This study can thus help in knowing the specific social aspects that prove to be crucial during LPS implementation and in understanding their interactions in the form of synergies and feedback loops.