[en] The purpose of this paper is to describe the development and application of a theoretical framework to examine the connections between different types of suppliers, their capabilities and opportunities in customer relationships, and the illustration of these connections through the findings from empirical case studies of small and medium-sized suppliers in the metal industry in Denmark. Multiple case studies involving 17 small and medium-sized suppliers within the Danish metal industry were undertaken. By focusing on the development of capabilities that are "valuable" to customers in specific types of supply, small and medium-sized suppliers may improve their responses to opportunities in their customer relationships. Further investigation is needed on the longer-term impacts of valuable capabilities on opportunity enactment by suppliers, and the examination of key issues arising from these findings across different industries and countries. Small and medium-sized suppliers, their customers and government agencies involved with suppliers should advocate and actively support the development of valuable capabilities to enhance the effectiveness of suppliers' relationship and network strategies and their potential to seize opportunities. This study highlights that different types of suppliers require different types of current and future valuable capabilities to seize opportunities and sustain current customers or develop new customer relationships.