A sole structure having a ground-facing surface and an upper-facing surface, the sole structure comprising: a sole member (106, 406, 906, 956) made from one or more parts and including a base surface, a medial side, and a lateral side, wherein the sole member (106, 406, 906, 956) includes a first sole part and a projection field engaged with or integrally formed with the first sole part, wherein the projection field comprises a plurality of projections that extend beyond the base surface and have exposed free ends, wherein the plurality of projections includes at least 20 projections having a projection packing density of at least 0.62 projections per square centimeter (4 projections per square inch) in the projection field, wherein a first subset of the plurality of projections have a length of at least 5 mm, and wherein at least a majority of the plurality of projections in the projection field readily bend under force applied by weight of a user of the sole structure; wherein the projection field includes a projection field base having a first surface and a second surface opposite the first surface, and wherein the plurality of projections originate at the second surface and extend from the projection field base in a direction away from the first surface and the second surface; wherein the base surface of the sole member (106, 406, 906, 956) includes an interior surface and an exterior surface opposite the interior surface, wherein the base surface has an opening defined through it that extends completely from the interior surface to the exterior surface, wherein the second surface of the projection field base is engaged with the interior surface of the base surface, and wherein the plurality of projections extend through the opening. a sole member (106, 406, 906, 956) made from one or more parts and including a base surface, a medial side, and a lateral side, wherein the sole member (106, 406, 906, 956) includes a first sole part and a projection field engaged with or integrally formed with the first sole part, wherein the projection field comprises a plurality of projections that extend beyond the base surface and have exposed free ends, wherein the plurality of projections includes at least 20 projections having a projection packing density of at least 0.62 projections per square centimeter (4 projections per square inch) in the projection field, wherein a first subset of the plurality of projections have a length of at least 5 mm, and wherein at least a majority of the plurality of projections in the projection field readily bend under force applied by weight of a user of the sole structure; wherein the projection field includes a projection field base having a first surface and a second surface opposite the first surface, and wherein the plurality of projections originate at the second surface and extend from the projection field base in a direction away from the first surface and the second surface; wherein the base surface of the sole member (106, 406, 906, 956) includes an interior surface and an exterior surface opposite the interior surface, wherein the base surface has an opening defined through it that extends completely from the interior surface to the exterior surface, wherein the second surface of the projection field base is engaged with the interior surface of the base surface, and wherein the plurality of projections extend through the opening.