Many are concerned about the large decline in K-12 student achievement since 2019. And rightly so, given what it signals about student learning and later life outcomes. Less noted is the pre-pandemic sustained decline in student achievement growth that followed 30 years of increases. We examine the nature of achievement decline as measured by national and state NAEP scores to better understand the magnitude of these pre-pandemic losses, where and when they occurred, and which students were most affected. We then discuss some of the hypothesized causes of the achievement declines and briefly reconcile these hypotheses with the available evidence. Our analysis suggests that pre-pandemic achievement declines are large, began earlier than commonly thought, vary substantially among states, and that a good portion of the pandemic learning losses have their roots well before 2020. These achievement declines likely result from several influences that vary across states and over time. Improving student achievement, especially among lower-performing students, will require a systematic shift in education policy.