We first purchased the 2-4T...but even though my son is 50% for his age in weight and 75% for height at age 2 1/2, it was too tight-fitting, so I exchanged for the 4-6.  Then it was TOO BIG!!! the head flopped down over his eyes--too top-heavy.  Plus, the 4-6 had ugly puke-green/tannish material for the paws.  It is warmer weight, so would be good in the northern states for Halloween.  But the colors were really cute... they just have really skewed sizes...the 4-6 was more for a large 6 year old.