IntegraL is a digital library system demonstrating a lightweight system integration technique for digital library collections and services. Digital library systems generally require integration with minimal or no changes to their code. IntegraL users see a totally integrated environment. They use their digital library system just as before. They also see extra link anchors. Selecting one generates a list of links to relevant meta-information (structural, content-based and knowledge-sharing relationships, and metadata). IntegraL generates the vast majority of supplemental link anchors and metainformation links automatically through the use of relationship rules. This paper presents the concept of meta-information, describes the IntegraL infrastructure and architecture supported by single sign-on authentication middleware, and explains how systems can integrate into the infrastructure. This research's primary contribution is providing a relatively straightforward, sustainable infrastructure for integrating digital library collections and services.