Cryo-EM data collection of the ASC-Caspase-1 CARD octamer was conducted at the HMS Cryo-EM Center. The CARD octamer sample (A280 = 0.2; 25 mM Tris-HCl pH 8.0, 150 mM NaCl, 2 mM DTT) was applied to a glow-discharged Quantifoil grid (R1.2/1.3 400-mesh gold-supported holey carbon, Electron Microscopy Sciences) blotted for 3–4 s under 100% humidity at 4 °C, and plunged into liquid ethane using a Mark IV Vitrobot (ThermoFisher). 5377 movies were acquired using a Titan Krios microscope (ThermoFisher) at an acceleration voltage of 300 keV equipped with a BioQuantum K3 Imaging Filter (slit width 20 eV), and a K3 direct electron detector (Gatan) operating in counting mode at 105,000 x (0.825 Å pixel size). Automated data collection with SerialEM varied the defocus range between −0.8 to −2.5 μm with two shots collected in each of four holes per stage movement through image shift. All movies were exposed with a total dose of 57.12 e-/Å2 for 1.897 s fractionated over 50 frames. Gain reference is "gain.mrc". Read-me file included "Readme.docx".