  Light and heavy pentaquarks are described within a constituent quark model
based on a spin-flavor hyperfine interaction. In this model the lowest state
acquires positive parity. The masses of the light antidecuplet members are
calculated dynamically using a variational method. It is shown that the octet
and antidecuplet states with the same quantum numbers mix ideally due to
SU(3)$_F$ breaking. Masses of the charmed antisextet pentaquarks are predicted
within the same model.
