Does generative AI narrow or widen productivity gaps in research? We study the distributional effects of AI on research productivity in economics using evidence from three sources: NBER working-paper and publication records, text-based measures of LLM-assisted writing, and an original survey of 227 academic economists measuring AI use across research tasks. We first show that productivity gaps among NBER authors narrowed following ChatGPT’s release: authors without research assistants (RAs) published a larger share of papers in top-tier journals, while authors from smaller teams gained in working-paper output and publication speed. We then use the survey to examine how individual AI use affects research productivity. We find weak evidence that AI affects working-paper output on average, but there is substantial heterogeneity. Triple-difference estimates show that greater AI exposure narrows the output gap between researchers with and without RAs but widens the gap between senior and junior researchers.…