To ascertain the role of the solidification cell structures on the mechanical performance of Al-Si-(Mg) alloys processed using the laser powder bed fusion (LPBF) technique, micropillar compression tests were performed on LPBF Al-10Si-0.3Mg (AlSi10Mg). The alloy's microstructure consists of submicron-scale cellular structures, dense dislocation networks, and dispersed nanoscale Si precipitates. The stress-strain responses of the micropillars are devoid of pronounced serrations and the yield strength and work hardening behaviors are size-independent. A comparison of the micropillar compression responses of the LPBF AlSi10Mg, 316 L stainless steel and Inconel 718 alloy, and nano-and micro-crystalline alloys is made. In LPBF AlSi10Mg, the combination of dislocation networks and shear-resistant Si particles resist the dislocation motion significantly and enhance dislocation storage. This results in the cellular structure dominating the strength and plastic flow. These results show a pathway for designing high strength alloys via additive manufacturing. Display omitted