Dynamic personality approaches provide an important step forward for twenty-first century personality theories because they promise greater explanatory power compared with latent trait approaches. Nevertheless, whether dynamic personality theories satisfactorily address motivated action remains unclear. To address this, this article discusses the logic of explanation and problems with latent trait approaches in terms of circularity and reification. The article then assesses explanation within dynamic personality accounts and the putative role of motivation. While dynamic personality approaches avoid many of the problems associated with latent trait accounts, a satisfactory account of motivational systems and “human nature” is currently missing. Suggestions for addressing the dynamics of human nature in terms of criteria for motivational systems are discussed. Attachment theory is offered as one possible foundation for addressing the motivational dynamics of personality. (PsycINFO Database Record (c) 2018 APA, all rights reserved)