This paper considers coexisting wireless networks sharing radio resources with contradicting performance objectives. A multi-objective optimization framework is proposed to investigate the fundamental trade-off between the performance of the coexisting networks. For a given set of radio resources, the optimal achievable performances of the coexisting networks are characterize by a multi-dimensional Pareto set. If the performance objectives of some of coexisting networks are modified or adjusted, the proposed framework provides the maximum corresponding achievable variation to the performance of the rest of coexisting networks. The quantitative information provided by the proposed framework facilitates joint design and optimization of coexisting networks and can be further exploited for regulating the collaborations among coexisting networks. We further show that the corresponding Pareto set can be in fact engineered by adjusting the technologies adopted in each of these networks. We then apply the proposed framework to two coexisting cellular networks. An improvement of 25% on the achievable rate is observed in return of a slightly higher interference tolerance at one of the coexisting networks.