Introduction: Our study examined the trajectories of plasma proteins relative to the onset and progression of amyloid deposition. By leveraging longitudinal blood samples and brain amyloid positron emission tomography (PET) scans from the Baltimore Longitudinal Study of Aging (BLSA), the present study examined trajectories of a broad set of neurodegenerative, immune, synaptic, and vascular plasma proteins relative to amyloid onset and progression.