Using the recently available wave of a large nationally representative sample of American elementary school children (ECLS-K data), this study examined the relationship between 6-7 year old students' behaviors exhibited in the 1st grade (approaches to learning, interpersonal skills, externalizing and internalizing behavior) and their reading and mathematics achievement at the end of the 5th grade (pupils aged 10-11 years), controlling for their achievement in the 1st grade. Findings include the single behavioral dimension that has a substantial association with later achievement is students' approaches to learning. The analysis of the interaction effects showed that students from families of low socioeconomic status, girls (in case of math) and minority students were more likely to have higher test scores given their improved approaches to learning. Further, the results demonstrated that basic skills (math and reading in the 1st grade) are substantial predictors of the 5th-grade approaches to learning. The findings reveal the complexity of the intertwined relationship between cognitive and behavior outcomes among young students and the long-term effects of early acquired skills and behaviors. (Contains 4 tables.)