Sole assembly with plural portions that cooperatively define chamber

A sole assembly for an article of footwear that includes an interior space that receives a foot of a wearer, the article of footwear also including an exterior surface, the sole assembly comprising:

• a first portion that includes a first surface that at least partially defines the interior space, the first portion also including a first chamber surface that opposes the first surface, the first portion further including a first mating surface, the first portion being made from a first material;
• and
• a second portion that includes a second surface that at least partially defines the exterior surface of the article of footwear, the second portion also including a second chamber surface that opposes the second surface, the second portion further including a second mating surface that is mated to the first mating surface such that the first chamber surface and the second chamber surface cooperate to at least partially define a substantially sealed chamber within the sole assembly, the second portion being made from a second material that is different from the first material.