To date, due to the lack of panel data, most micro-level empirical studies of technology adoption have used cross-sectional data. These studies cannot examine the dynamic processes of adoption such as learning. This article uses panel data to study the adoption of a new high-yielding variety seed. First, it establishes that learning is an important variable in the adoption process. Second, it establishes that cross-sectional estimates of a dynamic process are biased but that the extent of this bias may be small. Third, it illustrates the econometric methods needed to estimate a dynamic model when controlling for unobserved household heterogeneity.