A hallmark of macroautophagy is the formation of autophagosomes, double-membrane vesicles that enwrap cellular components destined for lysosomal degradation. We examined autophagosomal protein dynamics under various inducing stimuli using a comprehensive mass spectrometry-based proteomics approach in combination with functional studies in yeast and human cell cultures. Time frame and stimuli type influenced the autophagosome proteome, underlining the dynamic constitution of the organelle. We identified both a core set of proteins always localizing to autophagosomes and stimulus-dependent components that will serve as a resource for further characterization of the autophagosomal machinery and cargo selection. Among the core proteins were newly discovered autophagy regulators found to be conserved from yeast to humans, as well as the proteasome.