This paper focuses on supply flexibility, i.e., the ability of the purchasing function to respond in a timely and cost effective manner to the changing requirements of purchased components in terms of volume, mix and delivery date. Although sourcing strategies have been extensively analysed, the study of supply flexibility is in its infancy. The aim of this paper is to analyse how different sourcing practices are combined to form particular supply flexibility strategies. To do this, a survey among Spanish purchasing professionals was conducted. Three supply flexibility strategies ("integrated", "domestic" and "offshore") were identified and their relationship with contingent factors was investigated. The results show that Spanish firms have no single approach to achieve supply flexibility and that the type of flexibility achieved (supplier responsiveness, delivery policy and adaptability) depends on the strategy followed.