Background/Context: Postsecondary education plays a central role in income and wealth mobility (Chetty et al., 2017) and in buffering individuals from the negative effects of economic downturns (see recent evidence from BLS, 2019; BLS, 2020). Much of the policy and programmatic focus around college completion has centered on increasing the share of U.S. adults who earn their first postsecondary credential (see among others Bahr, 2014; Carruthers & Sanford, 2015; Dadgar & Trimble, 2014; Jacobsen & Mokher, 2009; Jepsen, Troske, & Coomes, 2014; Xu & Trimble, 2016). Yet an increasingly common but largely understudied set of policy efforts center on supporting adults with lower-level credentials to obtain additional education and training. This pattern of multiple credential accumulation is referred to within the higher education sector as "stacking" credentials. Seventeen states have allocated funding to colleges to develop stackable credentials pathways, and ten states require that their community college systems offer and advertise stacking options (Wilson, 2016). Several shifts in the labor market over the long- and short-term suggest stackable credentials could have meaningful economic returns to students. Technological advances may require additional postsecondary training among individuals who already hold a credential (Bartel, Ichniowski, & Shaw, 2007; Carnevale, Smith & Strohl, 2010; Deming & Noray, 2019). The sharper shift in employment demand and opportunities that arose in the midst of the COVID-19 pandemic and ensuing recession also highlights the need for additional workforce training for displaced workers as one solution to a faster economic recovery. Setting, Data, and Research Design: In this paper, we leverage a unique panel dataset provided by the Virginia Community College System (VCCS) that includes individual-level demographic information, graduation, and labor market outcomes for students who have enrolled at VCCS. The Virginia Community College System (VCCS) is comprised of 23 colleges across the Commonwealth, geographically distributed so that no Commonwealth resident lives more than 30 miles away from a college. Data for this study come from systemwide administrative records for the period from Fall 2000 to Spring 2019. These records include detailed information about each term in which a student enrolled, including program of study, courses taken, grades earned, credits accumulated, and financial aid received. The records also include basic demographic information, including gender, race, parental education, and zip code. Finally, we observe all credentials awarded by VCCS colleges beginning in 2000. In addition to the VCCS administrative records, we also have access to National Student Clearinghouse (NSC) and state unemployment insurance (UI) records provided by the Virginia Employment Commission (VEC) for all students. We employ a comparative individual fixed effects model to examine the impact of stacking on labor market outcomes. This approach compares the change in labor market outcomes for individuals who earn a second credential relative to their earnings and employment trajectory before stacking to the labor market trajectories of VCCS graduates who only earned one credential. Findings/Results: We find positive employment and wage returns to stacking, around a four percentage point increase in employment and $570 quarterly wage increase (around seven percent higher than the average non-stacker wages in the post period of about $8,000/quarter). Individuals stacking in Health and Business have higher returns about $640-760 quarterly wage increase, representing an almost nine percent wage increase relative to non-stackers earnings in both fields. Overall, we find little evidence of substantial differences in returns for female and male stackers, but substantially higher returns for White stackers and nearly no bene t for Black stackers on average. Returns are higher for those working adults whose first credential was a short-term or long-term certificate than for those who associate degree, for whom we find little evidence that a second credential improves employment or wages. We further leverage our administrative data to examine the relatedness of credentials within field and find that very specific stacking (two credentials in the same specific field of study -- for instance, two credentials as an emergency medical technician) yield higher returns than two credentials in the same broad field of study but with different specializations (for instance, a credential as an emergency medical technician and another as a phlebotomist, which are both Health professions). Conclusions: Our paper makes several primary contributions. First, our study provides the first casual estimates of which we are aware of the impact of stacking credentials on labor market outcomes for a broad range of community college programs and post-Great Recession cohorts. Second, our paper is an important and novel complement to a substantial body of prior work that has investigated the returns to community college credentials, but that to date has not focused on stacking. Our work extends the field's understanding of the returns to education by focusing on working adults' return to school and the relative benefit of stackable credential completion over course-taking. Third, given an increasing policy focus on adult education and training, our work highlights a pathway for increasing educational attainment and career training among working adults who have already a postsecondary credential.