Social ontology, by which I mean a subfield of contemporary analytic philosophy, is a comparatively small enterprise so far. That makes gathering a best-of-2019 list difficult. There just aren’t that many great papers coming out each year, or other notable events. Here are five highlights I could find. Feel free to send me an email and suggest other contributions to the field. I might update this entry later.
Brian Epstein’s paper “What are social groups? Their metaphysics and how to classify them” has been available as forthcoming for a while, but the official publication date has been 2019, which hopefully justifies including it in this list.
The International Social Ontology Society has started a Youtube channel this year and published keynotes from last years conference.
The Social Ontology conference in Tampere, organised by the European Network of Social Ontology. I believe the keynotes have been recorded, so there is hope that they will appear on ISOS Youtube channel at some point.
Finally, there has been a monist issue on the topic of Collective Responsibility and Social Ontology.
BONUS: Arto Laitinen has told me that a book symposium on Ásta’s Categories We Live By will soon appear in the Journal of Social Ontology (and dated as being from 2019).
 Two other publications on the ontology of groups deserve honourable mentions, even though they have appeared in 2018 (as forthcoming without a date yet in the first case). The first is Katherine Ritchie’s “Social Structures and the Ontology of Social Groups” and the second is Gabriel Uzquiano’s “Groups: Toward a Theory of Plural Embodiment”.