A supersonic molecular beam optical Stark measurement of the ($) over tilde A(2) Pi(r)-X(2) Sigma(+) band system of calcium monoacetylide CaCCH has been_performed. The determined values of mu are 3.01+/-0.03 D and 2.41+/-0.02 D for the ($) over tilde X(2) Sigma(+) and ($) over tilde A(2) Pi(1/2) states, respectively. A simple electrostatic model quantitatively predicts the ground and excited state dipole moments.