The purpose of this study is to investigate the effects of lean supply chain strategy. This empirical study used a sample of firms drawn from the automotive industry in Thailand and employed structural equation modelling to analyse the theoretical model. This study suggests that a model of the relationship between lean supply chain strategy and supply chain integration can be empirically established and that internal integration is a prerequisite of both supplier integration and customer integration. In addition, the findings suggest that firms do not necessarily have to follow the traditional sequence of the cumulative model of competitive capabilities. When lasting competitive capabilities have been sufficiently developed, they could contribute to the firm's performance. The research contributions provide a holistic view and systematic sequences of lean supply chain strategy implementation impacting on firms' performance in the emerging economies. The results of the research confirm that, in order to be successful in implementing lean supply chain strategy, firms need to be involved in strategic information sharing and integration with external firms. Importantly, the organisation must be internally cohesive before forming collaborative relationships with supply chain partners. The research also extends the traditional SSP theory in terms of supply chain integration that is created by adopting a firm's lean supply chain strategy. In addition, it supports and extends the RBV in the sense that resources must be utilised in a unique way, which in this case is integration. Also, it supports the RV in terms of collaborative relationships being a potential source of competitive advantage, since supply chain integration is considered to be a way of exploiting complementary resources and capabilities. Furthermore, the results can provide insight into and useful guidelines for key elements of internal integration, as well as demarcating a route for improving competitive capabilities and the firm's performance.