The present work proposes a multiobjective approach to solve the transmission expansion planning problem when investment costs and N-1 contingency criteria are considered. Given that both cost and security are conflicting objectives, the NSGA-II algorithm is used as the evolutionary multiobjective optimization technique to obtain a set of Pareto optimal expansion plans. The operative subproblem is solved with a high order interior point method for linear programming. The methodology is validated with the 6-bus Garver and IEEE 24-Bus systems, and the results show the effectiveness of the approach.