Learning objects (LOs), generally understood as digital learning resources shared and accessed through the Internet and reused in multiple learning contexts, have aroused enthusiasm in the field of educational technology. Although LOs offer many possibilities to change educational practices, there is a lack of empirical evidence on the effectiveness and usefulness of LOs. This paper reports results from three studies on effectiveness of LOs in various instructional settings. According to the results, there exists interaction between the effectiveness of LOs and various instructional arrangements. In order to be effective LOs require carefully designed learning environments and instructional arrangements. LOs themselves do not guarantee high quality learning performance and meaningful learning activities. It is the context of use together with instructional arrangements that defines the pedagogical value of LOs. (Contains 3 tables and 1 figure.)