Antibody-based therapies in Alzheimer’s disease target two protein species: amyloid beta (Aβ) and tau. While anti-Aβ therapies have been under investigation for many years, tau therapies have emerged only recently. The first human clinical trials of amyloid-targeting antibodies began in the early 2000s, but the first FDA approval of an anti-amyloid beta antibody therapy did not occur until 2021. This was followed by the approval of two more in 2023 and 2024. Currently, several other anti-Aβ antibodies are being studied in randomized clinical trials (RCTs) with a particular focus on treating individuals prior to the onset of clinical disease and improved methods for administering the therapies. Anti-tau therapies first entered human clinical trials in 2015, and there are currently several phase III trials in progress. This chapter reviews the rationale and progress for antibody and other trials in Alzheimer’s disease (AD) that target amyloid and tau.