A consumer is an individual entity with various motivations. This study is intended to incorporate a hierarchical structure of motivation to understand self-determined motivation for purchasing secondhand merchandise at thrift stores. A conceptual model adopted from Cadwallader et al. (2010)’s comprehensive model of motivation used in a marketing context was developed to investigate motivational process in secondhand merchandise shopping. The conceptual model includes the three levels of motivational structure–the global, contextual (environmental concern and frugality), and situational motivation. A series of the causal relationships among the three levels of self-determined motivations and buying intention to shop at thrift stores were hypothesized. A total of 219 respondents from two different northeastern state universities in the U.S. completed a self-administered survey. The results indicated that secondhand merchandise shopping is well explained in the hierarchical structure of self-determined motivation where the global motivation had a positive impact on the contextual motivations regarding environmental concern and frugality. Of the two contextual motivations, only environmental concern had a positive impact on situational motivation for shopping at thrift stores. Finally, the situational motivation positively influenced the intention to shop at thrift stores. The results of this model suggest that the hierarchical structure of self-determined motivation would be a very useful framework to understand consumer behavior for apparel shopping. Also, further research can be done to identify other contextual motivational factors to understand consumer motivation for shopping at thrift stores.