Stars are born surrounded by disks. These disks accrete mass onto the star as their dust evolves to eventually form planetesimals and planets. Accretion stops and disks dissipate after a few million years, so the fraction of stars surrounded by disks in a population of given age decreases with time. The detailed processes driving this overall picture are still not well understood, in part because we require large samples of disk-bearing stars at different ages to carry out studies of disk evolution in a meaningful way. We have surveyed the Orion OB1 association to obtain such samples, discovering and characterizing thousands of low-mass stars with ages between 1 and 10 Myr, ideal to study disk evolution and dissipation. I will describe several studies based on the information provided by these new samples and others from the literature. First, I will show our recent findings on the evolution of the dust in the innermost few au of disks, using the observed decrease of mass accretion with age as a constraint. Then, I will present the first results of our search for the lowest accretors, and describe what we are learning about the nature of the accretion flows and the inner disk in the final stages of primordial disks.
