A general method has been developed for the preparation of bis(syn‐proximally) functionalized calixarenes (6, 8–10). Starting from p‐tert‐butylcalixarene 1a and calixarene 1b syn‐proximally dialkylated calixarenes 2a and 2b, 4, and 5, respectively, were obtained by treatment with 4.2 equiv of NaH and 2.2 equiv of alkylating reagent in DMF. The syn‐proximal substitution pattern was unequivocally proven by an X‐ray structural determination of 2b. Furthermore the influence of different bases on the functionalization of the free hydroxyl groups of 2b with chloroacetone was studied. Cs2CO3 as the base gave the bis(syn‐proximally) functionalized calix‐arene 6 in the highest yield (82%). Cation complexation studies, with the picrate extraction method, showed that subtle changes in regioselective functionalization influences the selectivity for Na4 considerably.