Our comprehensive analysis of 23 studies and over 25,000 adults reveal that health literacy and eHealth literacy are distinct and complementary rather than interchangeable concepts. Though positively associated, we also found that measurement methods defined the relationship. To truly advance health equity, research, and intervention we must treat health literacy and eHealth literacy as separate constructs and measure them intentionally. We must also look beyond commonly identified personal factors, such as higher educational attainment, economic advantage, strong self-efficacy and positive health behaviors, to include environmental contexts that shape individual capability.