Utilizing SEIRA spectroscopy in combination with membrane models enabled us to detect the consequence of Aβmembrane interactions along early stages of the misfolding trajectory. Our approach revealed that incorporation into the membrane overall increases the relative content of β-sheets in Aβ three-fold already from the first contact with the membrane. Moreover, using the anisotropy of the backbone IR spectrum of β-sheets assisted by DFT-calculated spectra showed that the antiparallel to parallel β-sheet transition is promoted via a process that resembles a cooperative or autocatalytic mechanism, only when incorporation into the membrane is possible. As the transition from antiparallel to parallel β-sheets presents an important step along the misfolding trajectory, our data suggests that Aβ-membrane penetration may be a key factor in addition to the often-reported importance of negative surface charge of membrane interfaces. This supports earlier findings using fluorescently labelled Aβ species showing that toxic structures localize within the membrane. Nevertheless, the negative charge of membrane interfaces appears to further enhance the effects observed herein, as we note similar behavior of Aβ with neutral lipids, albeit to lesser extent.