We analyse whether research funding contests promote co-authorship. Our analysis combines Scopus publication records with data on applications to the Marsden Fund, the premiere source of funding for basic research in New Zealand. On average, and after controlling for observable and unobservable heterogeneity, applicant pairs were 13.8 percentage points more likely to co-author in a given year if they co-proposed during the previous ten years than if they did not. This co-authorship rate was not significantly higher among funded pairs. However, when we increase post-proposal publication lags towards the length of a typical award, we find that funding, rather than participation, promotes co-authorship.