Abstract Learning of user preferences has become a core issue in AI research. For example, recent studies investigate learning of Conditional Preference Networks (CP-nets) from partial information. To assess the optimality of learning algorithms as well as to better understand the combinatorial structure of CP-net classes, it is helpful to calculate certain learning-theoretic information complexity parameters. This paper provides theoretical justification for exact values (or in some cases bounds) of some of the most central information complexity parameters, namely the VC dimension, the (recursive) teaching dimension, the self-directed learning complexity, and the optimal mistake bound, for classes of acyclic CP-nets. We further provide an algorithm that learns tree-structured CP-nets from membership queries. Using our results on complexity parameters, we can assess the optimality of our algorithm as well as that of another query learning algorithm for acyclic CP-nets presented in the literature.