Much research has focused on nonnative speaker (NNS) use of modal verbs of obligation and necessity, indicating that NNSs may have difficulty with these modals and use them in different contexts from those of native speakers (NSs). Research also indicates that appropriate modal verb usage relies on presuppositions commonly known and accepted in a language community. This article proposes that NNS usage of modal verbs reflects the pragmatic frameworks and norms specific to the learner's L1 environment, which may be different from those expected in L2 conceptual structures. To determine whether NNS and NS usage of modals varies in relation to each other in the contexts of different topics, 455 essays written by speakers of Chinese, Japanese, Korean, Indonesian, and Vietnamese were compared to 280 essays on similar topics written by NSs of American English. The results of this study indicate that the usage of the root modals must, have to, should, ought to, and need to in NS and NNS writing appears to be culture and context dependent.