Selective formation for form II instead of form I paracetamol was promoted through the assistance of structurally related packing motifs and arrangements of paracetamol co-crystals in an aqueous solution. Form II paracetamol was produced by cooling crystallization in water with either oxalic acid or maleic acid. The co-crystal lattice structures of paracetamol with oxalic acid and maleic acid were similar to the packing pattern of form II paracetamol.