In comparison to other industries, construction sector encompasses a distinct, complex, and a competitive environment. It enriches the community with improvements when individuals with diverse perspectives, abilities, and degrees of construction expertise collaborate with each other. In this highly competitive multiparty context, conflicts have been labeled as one of the key constraints that prevent the `success of construction projects. Conflict is a fact that everyone must deal with on a regular basis. Construction projects are therefore not an exception. It entails different types of conflicts. To handle these different types of conflicts, construction professionals use different conflict handling styles. Therefore, the aim of this study is to investigate design team leaders’ preference of conflict handling styles and its impact on team spirit of the members of the design team during the post contract stage of building construction projects in Sri Lanka. To collect data, an e-based, closed-ended questionnaire was used incorporating the conflict handling styles introduced in Rahim's Dual Concern theory. The questionnaire was answered by 56 professionals who have the experience of working in the design team during the post contract stage. The study was limited to the building construction projects in Sri Lanka. To analyze the gathered data, descriptive statistics such as mean, percentage, count correlation co-efficient etc. were used. The study has revealed that during the post contract stage, the design team leaders use all five conflict handling styles of Rahim’s Dual concern theory: integrating style, obliging style, dominating style, avoiding style, and compromising style in different frequencies to handle conflicts among design team professionals. The design team professionals often use compromising style and rarely use integrating style, obliging style, dominating style, and avoiding style to handle conflicts among the design team professionals during the post contract stage respectively. Furthermore, the study indicates that these styles bring different levels of impact to the team spirit of design team professionals during the post contract stage of building construction projects in Sri Lanka. The team spirit of design team members is shown to be strongly affected by the compromising style. In contrast, the other four conflict handling styles, integrating style, obligating style, dominating style, and avoiding style, were identified to moderately impact team spirit. Moreover, findings revealed that all these five conflicts handling styles show a strong relationship with the team spirit of design team members during the post-contract stage of building construction projects in Sri Lanka. The research findings may assist construction industry design team leaders and other stakeholders to manage conflicts in a more efficient way and provide an insight to the way to handle conflicts to improve the team spirit of the design team during the post-contract stage of building construction projects in Sri Lanka. KEYWORDS: Conflicts, Conflict Handling Styles, Building Projects, Design team, Construction industry, Post contract stage.