We have measured a trigonometric parallax to the young brown dwarf 2MASSW J1207334-393254 .
The distance ( 54.0 ^ { +3.2 } _ { -2.8 } ~ { } pc ) and space motion confirm membership in the TW Hydrae Association .
The primary is a \sim 25 M _ { jup } brown dwarf .
We discuss the ” planetary mass ” secondary , which is certainly below the deuterium-burning limit but whose colors and absolute magnitudes pose challenges to our current understanding of planetary-mass objects .