Partially functionalized cavitands (7a–d) have been synthesized starting from the tetrakis(bromomethyl)cavitand 6. New cavitand‐based cation ligands, with one to three carbamoylmethylphosphane oxide (CMPO) moieties (11a–d), were prepared in good (66–90%) yields. The ligands 11a–d extract EuIII, but do so less effectively than the tetra‐CMPO cavitand 1. The decreasing number of CMPO groups which result in decreasing extraction percentages for EuIII, also decrease the selectivity of EuIII over that of FeIII, SrII, and UO2II. There is a difference in extraction behavior, determined by radio‐tracer experiments, between the distal and proximal disubstituted ligands, 11b and 11c, respectively. The extraction constants for the 1:1 complex of 11b and 11c with Eu(picrate)3 are Kex = 6.7 · 108 M−4 and 3.7 · 109 M−4, respectively.