Electronic device assemblies and methods including an organic substrate based space transformer are described. One assembly includes a space transformer comprising an organic substrate. The assembly also includes a carrier on which the space transformer is positioned, and a clamp positioned to couple the space transformer to the carrier. The assembly also includes a probe array positioned on the space transformer, wherein the space transformer is positioned between the probe array and the carrier. The assembly also includes a printed circuit board, wherein the carrier is positioned between the printed circuit board and the space transformer. The assembly also includes electrical connections to electrically couple the space transformer to the printed circuit board. Other embodiments are described and claimed.