A GJN is defined as "a group of individuals that accept the strategic objectives (top-level goals and aims) of the Global Jihad Movement and attempt to contribute to these from their country of residence." The leaders and members of a GJN do not formally belong to the hierarchical structure of al Qaeda or any other organization associated with the Global Jihad Movement, although they might have links to members of these organizations. GJN are capable of adopting flexible structures determined by the locations, preferences, and capabilities of network members. A study of the Madrid GJN highlights several key characteristics. Most of the members were legal residents in Spain, although none were born in Spain. Nationalities of the suspected jihadist linked to the bombings included Tunisians, Algerians, Egyptians, Syrians, and Moroccans; most were Moroccans recruited in Spain. Moroccans constitute the largest proportion of immigrants residing in Spain. None had attended a foreign jihadist training camp nor fought for the Global Jihad Movement abroad. Individual connections with persons in the larger Global Jihad Movement, however, contributed to the Madrid GJN acting under the strategic and perhaps operational influence of the central core leadership of the Global Jihad Movement. The strengths of GJNs are autonomy in operational and tactical command and control and no easily identifiable links to known terrorist organizations. Weaknesses of the GJN are a lack of professionalism and reliance on local personnel and resources, which makes their preparatory activities for attacks vulnerable to observation and suspicion from outsiders. 4 figures, 64 notes, and appended listing of the names of the 45 members of the Madrid GJN