The potential of new developments in mobile technology, with capabilities for anytime, anywhere wireless access, to affect pre-engineering education and technical literacy at the K-12 level remains poorly understood Mobile access to digital libraries provides unique opportunities for leveraging valuable experiences outside of the classroom. This paper presents a user needs analysis of teachers, students and parents with regard to understanding the potential of such mobile digital library services to enhance science and technology learning in informal environments for students in U.S. grades 4-5 and middle school To study this area we discuss a methodology at the intersection of design and research that borrows from qualitative research methods and traditional user-centered design, together with frameworks for translating qualitative data into concrete user needs. We present a summary of twelve need "themes" that emerged from the analysis together with recommendations for how these themes inform the development of a mobile digital library infrastructure and its digital learning resources. The recommendations are illustrated on an informal learning scenario intended for a pre-engineering exercise using resources ftom the NEEDS engineering education digital library at www.needs.org.