We first replicated the data analytic strategy used in Duncan et al. (2007) with a population-based data set of French-speaking children from Quebec (Canada). Prospective associations were examined between cognitive, attention, and socioemotional characteristics underlying kindergarten school readiness and second grade math, reading, and general achievement. We then extended this school readiness model by including motor skills as an additional element in the prediction equation and expanded the original strategy by including classroom engagement. The Montreal Longitudinal-Experimental Preschool Study, featured in Duncan et al., served as the Canadian reference group. In the replication model, kindergarten cognitive and attention characteristics predicted achievement by the end of 2nd grade. Although inconsistent across outcomes, behavioral problems and skills also emerged as predictors of some aspects of later achievement. Coefficients for kindergarten math skills were largest, followed by attention skills, receptive language skills, attention problems, and behavior. Most coefficients resembled those generated in the initial study. In our extension model, fine motor skills added their significant contribution to the prediction of later achievement above and beyond the original key elements of school readiness. Our extension model confirmed prospectively associations between kindergarten cognitive, attention, fine motor, and physical aggression characteristics and later achievement and classroom engagement by the end of 2nd grade. Although they comparatively showed better long-term benefits from stronger early attention skills, girls with less kindergarten cognitive skills were more vulnerable than boys with similar deficits when predicting 2nd grade math.