Wikipedia is a well-known platform for disseminating knowledge, and
scientific sources, such as journal articles, play a critical role in
supporting its mission. The open access movement aims to make scientific
knowledge openly available, and we might intuitively expect open access to help
further Wikipedia's mission. However, the extent of this relationship remains
largely unknown. To fill this gap, we analyze a large dataset of citations from
Wikipedia and model the role of open access in Wikipedia's citation patterns.
We find that open-access articles are extensively and increasingly more cited
in Wikipedia. What is more, they show a 15% higher likelihood of being cited in
Wikipedia when compared to closed-access articles, after controlling for
confounding factors. This open-access citation effect is particularly strong
for articles with low citation counts, including recently published ones. Our
results show that open access plays a key role in the dissemination of
scientific knowledge, including by providing Wikipedia editors timely access to
novel results. These findings have important implications for researchers,
policymakers, and practitioners in the field of information science and
technology.