["Agribusiness, EarlyView. ", "\nABSTRACT\nMaize is Tanzania's primary food crop, and plays a pivotal component of national food security, yet production remains characterized by low‐efficiency and exposure to climatic variability. Using a two‐period panel data (2008 and 2012) from the Living Standards Measurement Study‐Integrated Surveys on Agriculture (LSMS‐ISA), we investigate whether the timing of adoption of improved maize seed varieties affects farm output and productivity. We first implement propensity score matching (PSM) to construct comparable groups of adopters and non‐adopters. We then classify farmers into early, late, and never adopters and estimate a Difference‐in‐Differences model embedded within a True Random Parameters Stochastic Production Frontier (TRP‐SPF) framework to account for unobserved heterogeneity. Adoption of improved seeds is associated with higher Total Factor Productivity (TFP) growth, and adoption timing matters. Late adopters experience the strongest productivity gains. Average TFP increased by 7.67% per year over the period, driven primarily by the adoption of improved seed variety (10.31% per year), while improvements in technical efficiency (TE) remained modest (1.45% per year). Human capital, climatic effects, TE, scale efficiency, and the production environment also contribute to productivity dynamics.\n"]