The authors discuss the vast application potential of multipurpose smart eyeglasses that integrate into the form factor of traditional spectacles and provide frequently needed sensing and interaction. In combination with software apps running on smart eyeglasses, the authors develop universal assistance systems that remain unobtrusive and thus can support wearers throughout their daily life. They describe a blueprint of the embedded architecture of smart eyeglasses and identify various software app clusters. They discuss findings from using smart eyeglasses prototypes in three case studies: to recognize cognitive workload, quantify reading habits, and monitor light exposure to estimate the circadian phase. This article is part of a special issue on digitally enhanced reality.