This paper offers a cross-country and cross-disciplinary analysis of the development of open access publishing from 2000 to 2019. Through an analysis of seven world regions and nine scholarly felds, we found that, while the overall share of open access journals has increased signifcantly over the last two decades, there are important diferences across both the analyzed world regions and disciplines. We also found that, with the exception of neuroscience, the proportion of open access journals is considerably lower among the journals ranked in the Q1 quartile of Scopus than in the general feld. We also ofer a model that explains the development of open access publishing trends on diferent disciplinary and geographical levels.