Different firms have implemented environmental programmes (such as design to recycle, life cycle analysis or environmental certification) and social practices (such as programmes aimed to improve employees' working conditions or projects to support the external community). This study aims to analyse the impact of these programmes on each dimension of the triple bottom line (environmental, social and economic performance). It extends the extant literature by (1) considering environmental and social initiatives in the same study, (2) analysing their impact on the three pillars of the triple bottom line, (3) comparing the impact of internal and external programmes, and (4) analysing sustainable operational projects at the plant level. The data used were obtained from the fifth (2009) round of the International Manufacturing Strategy Survey (IMSS) which includes responses from manufacturing plants within the assembly industry in 19 countries. Our findings suggest that internal environmental programmes have a positive impact on the three components of the triple bottom line, whereas internal social initiatives have a positive impact on only two components: Social and environmental performance. It seems that firms still need to achieve positive financial gains from these social programmes. Finally, regarding the external or supply chain initiatives, our results show that supply chain assessment has no impact on the triple bottom line, unlike supply chain collaboration which contributes to improve all three elements. Two important managerial contributions can be derived from this study: (1) Managers have to be aware of the possible negative effects (on the short term) of social practices on manufacturing costs, and (2) they need to implement collaborative practices with their supply chain partners, as assessment alone has been found not to have any impact on the triple bottom line.