This study investigates whether lesson structure (LS) matters and which components are important for academic engagement during the first grade of secondary education. Data from videoed lessons of 10 Dutch and 12 Indonesian teachers analyzed using an observation protocol show that six LS components are found, that between class and over measurement variability in LS is evident, and that on average LS change is not a linear function of time. Class differences over time do exist and several personal and contextual characteristics affect LS. Links between LS (student work time, reviewing and introducing new content) and academic engagement are evident. (Contains 10 tables and 3 figures.)