Because students from American Indian/Alaska Native (AI/AN) backgrounds tend to lag behind their peers in academic achievement, researchers have recommended integrating Native Language and Culture (NLC) into instruction. However, existing evidence from large-scale studies finds a "negative" effect of the use of NLC on achievement, although this research does not take into account aspects of student background and the learning context. Using a nationally representative dataset, we found that use of NLC had a less negative and/or more positive effect on achievement among students whose families identified more strongly with their Native culture and who were in schools with larger percentages of AI/AN students. Our results support earlier contentions that the use of NLC can be effective in enhancing achievement for at least some AI/AN students; they also suggest that existing approaches to NLC should be expanded to accommodate AI/AN students in a wider range of contexts. [This paper was published in "Journal of American Indian Education" v56 n2 2017.]