Academic underachievement has fascinated and frustrated those in gifted education for decades, capturing the attention of educators, researchers, and policy makers alike (McCoach & Siegle, 2003). A topic of interest in education as far back as the 1950s (Gowan, 1955), underachievement is often framed in terms of lost personal and societal potential. It has been 20 years since the publication of Reis and McCoach's (2000) seminal piece in Gifted Child Quarterly on academic underachievement in gifted education, in which they grappled with conceptual and operational definitions, causes and correlates, and review of educational techniques. To date, that article has been cited roughly 800 times, a clear indicator that this question remains timely and relevant. Research into gifted underachievement has remained fairly siloed from research on achievement motivation over the years (c.f. Borkowski & Thorpe, 1994; Preckel et al., 2006). For example, achievement motivation researchers frequently use the term "underachievement" without careful attention to how it is conceptualized and operationalized as an ability-achievement distinction (e.g., Paunesku et al., 2015). Additionally, it is not uncommon to hear gifted underachieving students described as "lacking" motivation (e.g., Whitmore, 1986). In a way, this mirrors the oft-repeated misconceptions that all gifted students are motivated, and that motivation is static as students move through K-12 schooling and beyond (Muenks et al., 2018; Snyder & Linnenbrink-Garcia, 2013). Over time, the slow integration of work on underachievement and motivation proved insightful (e.g., Clinkenbeard, 2012; Garn et al., 2010; Preckel et al., 2006) and ultimately led to the creation of this special issue on Underachievement and Achievement Motivation. The authors of articles in this special issue study gifted underachievement and achievement motivation using a variety of analytic methods, theoretical lenses, developmental periods, and learning contexts. Including a range of conceptual and methodological approaches was intentional on our part, through our hope that probing a topic from multiple angles would lead to a richer understanding of the phenomenon and potential means to decrease it in the future. It is our hope as coeditors of this special issue that this collection of articles is only the beginning of more focused inquiry, fruitful collaborations across traditional silos, and insights into the developmental roots, differential trajectories, contextual influences, and development of techniques used to alleviate underachievement.