This chapter analyzes paradiplomacy of Mexican states comparatively, studying inter-institutional agreements. It describes the amount of IIAs concluded by Mexican SSGs, as well as the level of government (state or municipal) that signed the agreement, and if it is a sisterhood agreement or other type. It underscores the fact that most IIAs have been signed by the same few SSGs, especially those with the highest levels of paradiplomacy. It also analyzes how the negotiation and signing of IIAs has evolved through time; its central finding is that the rate of negotiation and signing of IIAs has increased in the last years. It then studies foreign partners, both in terms of whether they are governmental or non-governmental, and in their geographic location; most of the external partners are SSGs, and most of the activities of Mexican SSGs, like Mexican foreign policy, are concentrated with partners in the Americas, especially the USA. Next, the areas of cooperation are analyzed, finding that most IIAs are concluded in areas where the SSGs have powers to do so, particularly those that have a direct effect on the welfare and development of the SSG (cooperation in education, culture, science and technology, as well as promotion of trade, investment and tourism).