A sole structure for an article of footwear, the sole structure comprising: a midsole having an upper surface, an opposite lower surface, and an outer edge, the midsole further comprising an upper portion and a lower portion; an elongate insert having an upper flange and a lower flange, a horizontal flange and a pair of stability fins; wherein: (i) the midsole outer edge extends between the upper surface and the lower surface and further includes a forefoot portion, a medial portion, a lateral portion, a heel portion and an inwardly-extending elongate groove that is continuously disposed along the medial portion, the heel portion and the lateral portion; (ii) the elongate groove partitions the midsole and defines the upper portion, the lower portion and a central base portion of the midsole; (iii) the upper portion and the lower portion are spaced from each other along the elongate groove and are joined to each other at the central base portion; (iv) the upper flange and the lower flange have outer edges that are joined together at a joined region; (v) the horizontal flange is located in the joined region and extends inward into the midsole; (vi) the pair of stability fins are compressible and extend between the upper flange and the lower flange, one stability fin being disposed on a medial side of the sole structure and the other stability fin being disposed on a lateral side of the sole structure; (vii) the elongate insert is a continuous structure that conforms to the elongate groove and extends around the medial portion, the heel portion and the lateral portion; (viii) an inner surface of the elongate insert is secured to the midsole outer edge within the elongate groove; and (ix) the upper flange outer edge extends toward a peripheral edge of the midsole upper portion (70, 72) and the lower flange outer edge extends toward a peripheral edge of the midsole lower portion (75, 77). a midsole having an upper surface, an opposite lower surface, and an outer edge, the midsole further comprising an upper portion and a lower portion; an elongate insert having an upper flange and a lower flange, a horizontal flange and a pair of stability fins; wherein: (i) the midsole outer edge extends between the upper surface and the lower surface and further includes a forefoot portion, a medial portion, a lateral portion, a heel portion and an inwardly-extending elongate groove that is continuously disposed along the medial portion, the heel portion and the lateral portion; (ii) the elongate groove partitions the midsole and defines the upper portion, the lower portion and a central base portion of the midsole; (iii) the upper portion and the lower portion are spaced from each other along the elongate groove and are joined to each other at the central base portion; (iv) the upper flange and the lower flange have outer edges that are joined together at a joined region; (v) the horizontal flange is located in the joined region and extends inward into the midsole; (vi) the pair of stability fins are compressible and extend between the upper flange and the lower flange, one stability fin being disposed on a medial side of the sole structure and the other stability fin being disposed on a lateral side of the sole structure; (vii) the elongate insert is a continuous structure that conforms to the elongate groove and extends around the medial portion, the heel portion and the lateral portion; (viii) an inner surface of the elongate insert is secured to the midsole outer edge within the elongate groove; and (ix) the upper flange outer edge extends toward a peripheral edge of the midsole upper portion (70, 72) and the lower flange outer edge extends toward a peripheral edge of the midsole lower portion (75, 77). (i) the midsole outer edge extends between the upper surface and the lower surface and further includes a forefoot portion, a medial portion, a lateral portion, a heel portion and an inwardly-extending elongate groove that is continuously disposed along the medial portion, the heel portion and the lateral portion; (ii) the elongate groove partitions the midsole and defines the upper portion, the lower portion and a central base portion of the midsole; (iii) the upper portion and the lower portion are spaced from each other along the elongate groove and are joined to each other at the central base portion; (iv) the upper flange and the lower flange have outer edges that are joined together at a joined region; (v) the horizontal flange is located in the joined region and extends inward into the midsole; (vi) the pair of stability fins are compressible and extend between the upper flange and the lower flange, one stability fin being disposed on a medial side of the sole structure and the other stability fin being disposed on a lateral side of the sole structure; (vii) the elongate insert is a continuous structure that conforms to the elongate groove and extends around the medial portion, the heel portion and the lateral portion; (viii) an inner surface of the elongate insert is secured to the midsole outer edge within the elongate groove; and (ix) the upper flange outer edge extends toward a peripheral edge of the midsole upper portion (70, 72) and the lower flange outer edge extends toward a peripheral edge of the midsole lower portion (75, 77).