An article of footwear for a user, comprising: a front end; a rear end; a sole structure; an upper attached to the sole structure, the upper defining a forefoot region, a midfoot region, and a heel region of the article of footwear, the upper and the sole structure together defining an interior cavity; and a strap system engaged with the upper, the strap system comprising a strap extending around the heel region and configured to tighten portions of the upper in response to the user's foot engaging the strap system within the interior cavity in one of the forefoot region or the midfoot region, characterized in that the strap system comprises: a rail positioned at least partially within the interior cavity and including a base portion, the base portion movable between a first position and a second position based on the user's toe movement within the interior cavity; and a strap coupled to the rail and configured to tighten the portions of the upper based on a location of the base portion; or in that the strap system comprises: a stirrup region positioned within the interior cavity, the stirrup region comprising a loop that receives the user's foot as it is inserted into the article of footwear; and a tightening region positioned outside the interior cavity and coupled to the stirrup region, the tightening region engaged with the upper in order to cause the upper to tighten around the user's foot along the midfoot region and the heel region of the upper in response to movement of the stirrup region. a front end; a rear end; a sole structure; an upper attached to the sole structure, the upper defining a forefoot region, a midfoot region, and a heel region of the article of footwear, the upper and the sole structure together defining an interior cavity; and a strap system engaged with the upper, the strap system comprising a strap extending around the heel region and configured to tighten portions of the upper in response to the user's foot engaging the strap system within the interior cavity in one of the forefoot region or the midfoot region, characterized in that the strap system comprises: a rail positioned at least partially within the interior cavity and including a base portion, the base portion movable between a first position and a second position based on the user's toe movement within the interior cavity; and a strap coupled to the rail and configured to tighten the portions of the upper based on a location of the base portion; or in that the strap system comprises: a stirrup region positioned within the interior cavity, the stirrup region comprising a loop that receives the user's foot as it is inserted into the article of footwear; and a tightening region positioned outside the interior cavity and coupled to the stirrup region, the tightening region engaged with the upper in order to cause the upper to tighten around the user's foot along the midfoot region and the heel region of the upper in response to movement of the stirrup region. a rail positioned at least partially within the interior cavity and including a base portion, the base portion movable between a first position and a second position based on the user's toe movement within the interior cavity; and a strap coupled to the rail and configured to tighten the portions of the upper based on a location of the base portion; or in that the strap system comprises: a stirrup region positioned within the interior cavity, the stirrup region comprising a loop that receives the user's foot as it is inserted into the article of footwear; and a tightening region positioned outside the interior cavity and coupled to the stirrup region, the tightening region engaged with the upper in order to cause the upper to tighten around the user's foot along the midfoot region and the heel region of the upper in response to movement of the stirrup region. a stirrup region positioned within the interior cavity, the stirrup region comprising a loop that receives the user's foot as it is inserted into the article of footwear; and a tightening region positioned outside the interior cavity and coupled to the stirrup region, the tightening region engaged with the upper in order to cause the upper to tighten around the user's foot along the midfoot region and the heel region of the upper in response to movement of the stirrup region.