Complex coacervate core micelles form in aqueous solutions from poly(acrylic acid)-block-poly(acrylamide) (PAA_xPAAm_y, x and y denote degree of polymerization) and poly(N,N-dimethyl aminoethyl methacrylate) (PDMAEMA₁₅₀) around the stoichiometric charge ratio of the two components. The hydrodynamic radius, R_h, can be increased by adding oppositely charged homopolyelectrolytes, PAA₁₄₀ and PDMAEMA₁₅₀, at the stoichiometric charge ratio. Mixing the components in NaNO₃ gives particles in highly aggregated metastable states, whose R_h remain unchanged (less than 5% deviation) for at least 1 month. The R_h increases more strongly with increasing addition of oppositely charged homopolyelectrolytes than is predicted by a geometrical packing model, which relates surface and volume of the particles. Preparation in a phosphate buffer – known to weaken the electrostatic interactions between PAA and PDMAEMA – yields swollen particles called complex coacervate core micro-emulsions (C3-μEs) whose R_h increase is close to that predicted by the model. These are believed to be in the stable state (lowest free energy). A two-regime increase in R_h is observed, which is attributed to a transition from more star-like to crew-cut-like, as shown by self-consistent field calculations. Varying the length of the neutral and polyelectrolyte block in electrophoretic mobility measurements shows that for long neutral blocks (PAA₂₆PAAm₄₀₅ and PAA₃₉PAAm₃₈₁) the ζ-potential is nearly zero. For shorter neutral blocks the ζ-potential is around −10 mV. This shows that the C3-μEs have excess charge, which can be almost completely screened by long enough neutral blocks.