Experimental activation parameters for the intramolecular Diels-Alder reactions of 1,3,8-nonatriene, 1,3,9-decatriene, and 1,3,10-undecatriene have been measured, and the Monte Carlo-Jumping between Wells/Stochastic Dynamics [MC(JBW)/SD] method, which gives relative free energies of activation, was tested as a means to predict stereoselectivities. The predictions are compared to experimental results, and to predictions from quantum and molecular mechanics methods.