In the non‐amyloidogenic pathway, the Alzheimer's amyloid precursor protein (APP) is cleaved within the amyloid‐β domain by α‐secretase precluding deposition of intact amyloid‐β peptide. The large ectodomain released from the cell surface by the action of α‐secretase has several neuroprotective properties. Studies with protease inhibitors have shown that α‐secretase is a zinc metalloproteinase, and several members of the adamalysin family of proteins, tumour necrosis factor‐α convertase (TACE, ADAM17), ADAM10, and ADAM9, all fulfil some of the criteria required of α‐secretase. We review the evidence for each of these ADAMs acting as the α‐secretase. What seems to be emerging from numerous studies, including those with mice in which each of the ADAMs has been knocked out, is that there is a team of zinc metalloproteinases able to cleave APP at the α‐secretase site. We also discuss how upregulation of α‐secretase activity by muscarinic agonists, cholesterol‐lowering drugs, steroid hormones, non‐steroidal anti‐inflammatory drugs, and metal ions may explain some of the therapeutic actions of these agents in Alzheimer's disease. © 2003 Wiley‐Liss, Inc.