This preface for the proceedings of the first international workshop on Modular Knowledge (MK2022) presents the content of the workshop and reports on the results of the interactive sessions that took place during the event. The dramatic increase in the amount of open and linked data and the increasing semantification of such data make clear that knowledge is not monolithic, static or uniform. This requires a renewed push for dealing with heterogeneous and distributed knowledge as a constellation of modules. Each module stores a portion of knowledge about one particular subdomain, described in a specific schema, and valid under a set of circumstances. In such a scenario we need well-founded conceptual approaches and practical techniques for modular knowledge management, for example, to recognize relevant partitions of a monolithic knowledge source, but also to define a modularized vision of the domain qualifying the knowledge with a given situation or agent, integrating heterogeneous modules of knowledge, including knowledge represented in sub-symbolic models. The discussion of such modularity notions and techniques, their development and exploitation are the focus of the proposed Modular Knowledge workshop. The Modular Knowledge workshop combines the efforts of previous experiences (like WoMO, ARCOE-Logic and WOMoCoE workshops) into an interdisciplinary venue for discussing and developing solutions for modularity of knowledge. The workshop series aims at covering the use of various approaches (ranging from rich semantic representations, like Knowledge Graphs and formal ontology, to simpler schemas, like RDF and database schemas) for representing knowledge, its context, its evolution, and for making it accessible to automatic reasoning and knowledge management tasks. The Modular Knowledge workshop covers logic-based languages as well as subsymbolic and numerical representations.