Background <p>There is a pressing need to scale-up health and human services. While there are many scale-up frameworks in the broader literature, most of the general scale-up frameworks treat scale-up as a linear process. There are calls to bolster research viewing scale-up as a dynamic process. The purpose of this review is to consolidate and apply systems thinking to existing scale-up frameworks to illustrate feedback relationships among the drivers of scale-up.</p> Methods <p>We used a scoping review informed by hermeneutic principles to search the literature for scale-up determinants. We searched six scholarly databases (Medline, Web of Science, Embase, CINAHL, PsycInfo, and Google Scholar) for review articles of scale-up frameworks that yielded key determinants of scale-up. We also included other scale-up papers that yielded determinants. Articles that did not meet these criteria were excluded during the title/abstract and full-text screening process. Two coders assessed each article before it was excluded. Two coders extracted the scale-up determinants and definitions. We used thematic analysis to code and consolidate the determinants. Then we used an ex-post development approach to create a causal loop diagram (CLD) visualizing the scale-up determinants and feedback structures.</p> Results <p>Our search yielded 2693 articles which resulted in a usable sample of 40 articles after the screening process. The 40 articles contained 1053 scale-up determinants. Our coding procedures and CLD reduced these determinants to 25 in our model. There are six reinforcing loops and three balancing loops that are at play in scale-up efforts depicted in the final CLD. Among the determinants, motivation, capacity, enabling environment, and alignment were prominent.</p> Conclusions <p>The resulting interpretation and CLD provide a dynamic conceptualization of scale-up complexity, highlighting key leverage points in the scale-up process.</p>