Abstract: A footwear assembly requires a wearer to adjust in order to maintain stability while standing, walking, etc. The assembly includes an outer sole having a flexible shell surrounding a hollow interior substantially filled by a plurality of unconnected, substantially non-deformable particles. Foot pressure applied to the outer sole results in movement of the plurality of particles, and the resiliency of the shell allows it to assume a variety of different configurations based in part on the portion to which pressure is applied. The resiliency of the shell further facilitates normal biasing thereof and the particles therein into a normal, non-compressed orientation. The tendency of the outer sole to assume a variety of different configurations will, in some circumstances, require a wearer to adjust the corresponding foot and/or leg in order to maintain normal stability, at least when foot pressure is applied to the outer sole.