It's a staggering statistic -- 36 million adults in the United States read at a 3rd grade level or below. Of these, more than two-thirds are members of the workforce but don't have the skills for advancement. Yet, finding and completing education programs is often a struggle for this population. Access to quality education programs is limited at best -- our current adult education programs can only handle about four million of those 36 million learners. And, because they often juggle multiple jobs and family duties, staying in and finishing a program is a challenge for most. Additionally, much of what these students are learning does not align with the skills they need for today's workforce. So, often students (who may not be confident in their learning skills) struggle through courses that ultimately don't help them get to the next level. The use of technology to support learning for K-12 students is gaining popularity, leading many to ask whether there might be similar solutions for low-skilled adults. Although in general these learners haven't had regular access to technology and broadband, recent surveys indicate that increasingly they own smartphones and use them to access the Internet, download apps, and learn. Research about adults as learners can inform the design of effective digital learning experiences. The design principles outlined in this report are based on the five prevailing theories about how adults learn: andragogy, experiential learning, self-directed learning, transformational learning, and neuroscience.