  The effect of antiferromagnetic interchain coupling in alternating spin
(1,1/2) chains is studied by mean of spin wave theory and density matrix
renormalization group(DMRG). Two limiting cases are investigated, the two-leg
ladder and its two dimensional (2D) generalization. For the 2D case, spin wave
approximation predicts a smooth dimensional crossover keeping the ground state
ordered, whereas in the ladder case the DMRG results show a gapped ground state
for any $J_{\perp}>0$. Furthermore, the behavior of the correlation functions
closely resemble the uniform spin-1/2 ladder. However, for small $J_{\perp}$,
the gap behaves quadratically as $\Delta\sim0.6 J^2_{\perp}$. Similarly to
uniform spin chains, it is conjectured an analogous spin gap behavior for an
arbitrary number of mixed spin chains
