This article analyzes the cooperative mechanisms operating in the Malacca Strait in three chapters. Chapter 1 introduces the definitions of ”piracy” and ”armed robbery against ships” under international law and points out the differences between them. Specifically, the term ”piracy,” as opposed to ”armed robbery against ships,” means: (a) illegal acts of violence, detention, or depredation, (b) committed for private ends(c) by crewmembers or passengers of a private vessel or aircraft, (d)on the high seas or outside the jurisdiction of any state, (e) against another vessel or aircraft. Chapter 2 presents an analysis of the legal status of the Malacca Strait under the United Nations Convention on the Law of the Sea(”UNCLOS”)and the two competing schools of thought regarding acts of depredation in these waters. One theory sees Exclusive Economic Zones (”EEZs”) as a part of the high seas; therefore, acts of depredation within this zone are considered ”piracy” under international law, subject to the common jurisdiction of all states. The other theory recognizes the jurisdiction of the littoral state(s) within the EEZ under Art 56 of the UNCLOS; under this theory, acts of depredation within this zone are ”armed robberies against ships,” which falls under the exclusive jurisdiction of the littoral state(s). Chapter 3 looks at the unilateral, bilateral, trilateral and multi-lateral cooperative mechanisms undertaken by the littoral states throughout the years to combat piracy and armed robbery against ships in the Malacca Strait. These include collaborations among the three littoral states, such as the Maritime Operation Planning Team and Joint Anti-Piracy Patrols and Information Sharing System, both established in 1992, and regional multi-lateral mechanisms such as the Association of Southeast Asian Nations (”ASEAN”), which formally began to combat piracy as an international crime after its 1998 Ministerial Meeting on Transitional Crime. In the early 2000s, the littoral states and users of the Malacca Strait, led by Japan, held a series of summits to discuss cooperative mechanisms to combat piracy and armed robbery of ships in the region. In 2004, sixteen countries signed onto the Regional Cooperation Agreement on Combating Piracy and Armed Robbery against Ships in Asia (”ReCAAP”), the first intergovernmental agreement of its kind. The Information Sharing Center (”ISC”) was created under ReCAAP, the background, organization, and functions of which are discussed in Chapter 3. This article concludes by suggesting that stakeholders further collaborate in areas such as legal aid, law enforcement, and institutional capacity-building, in order to sustain the momentum of cooperation on combating piracy and armed robbery against ships in the Malacca Strait.