Phenomenological investigations about social reality could be argued to center around three general concepts: Social and Institutional Facts, Collective Intentionality and Values. Even though it is certainly not possible to speak of one unified theory that phenomenology as such puts forward about social reality, the systematic interconnections between these concepts make the single contributions of phenomenologists tesserae of a larger mosaic. This introduction is an attempt to sketch this mosaic by situating these notions within the debate about social ontology as conducted by phenomenologists roughly from 1910 to 1927. It also highlights the systematic connections between phenomenological insights and contemporary discussions on social ontology.