We present the results of a quark model study of L=1 mesons with one heavy quark. We give the masses of these states as predicted by the relativized quark model and the decay properties as calculated using both the pseudoscalar emission model and the flux-tube-breaking model. We examine the idealized limit of one infinitely massive quark and one light quark and discuss our results in this context as a guide to what can be learned from the study of these states. We find that, even for B mesons, the tensor interactions play an important role in the spectroscopy and the mQ has not yet been reached. We conclude that further experimental study of the decay properties of the D1 mesons is important to the understanding of the P13-P11 mixing mechanism.