The effect of second-phase particle clustering on the formability of four ‘model’ Al-Si alloy sheets is evaluated using metallographic image analysis and mechanical testing methods. Spatial tessellation and dilational counting techniques are applied to large-scale high-resolution digital particle fields in order to obtain explicit, statistically significant measures of second-phase particle clustering at several orders of magnitude. Overall, results indicate that the size, aspect ratio, orientation, and spatial distribution of first-order clusters in the Al-Si alloys under study have a significant impact on foimability behaviour through their intrinsic promotion of void nucleation, growth, and coalescence. A general divergence in forming limits with increasing tensile minor strains is observed, suggesting that void damage is a predominant factor in the onset of strain localization at the forming limits due to the direct relationship between void rates and stress triaxiality. A strong association between first-order clusters and voids in both undeformed and deformed Al-Si microstructures supports the significance of secondphase pmticle clustering on void damage evolution. Furthermore, it is found that the promotion of void damage within first-order clusters results in a direct correspondence between preferential orientation of high aspect ratio first-order clusters and relative levels of anisotropy within forming limit data.