In an effort to provide background information about Mexican organized crime groups primarily responsible for the increase in violence, we have developed the following resources. We recognize from the outset that it is extraordinarily difficult to provide exact, even verifiable information about organized crime groups who, because of the nature of their illicit activities, operate secretively. Nevertheless, while acknowledging these limitations, we felt it would be useful to provide some of the most credible information and research available on organized crime in Mexico and to update it from time to time as the situation changes.

In this context, we make the following general assumptions about the criminal organizations operating in Mexico:

1) While it is common to refer to the criminal groups as "cartels" or "drug trafficking organizations (DTOs) we prefer to talk about organized criminal groups (OCG). The OCGs operating in Mexico are similar to the DTOs described by the U.S. government, but their activities are not limited to trafficking in illicit drugs and extend to smuggling and trafficking in humans; kidnapping, extortion, and trafficking in stolen and pirated goods, as well as natural resources, amongst many others.

2) OCGs are primarily trafficking businesses that are motivated by profits. They seek to move illicit products to the consumer market, principally, but not exclusively, in the United States. In most cases, the OCGs operating in Mexico are well organized, well financed and operate trans-nationally. However, they are generally not vertically integrated organizations, but horizontally integrated, allowing them to "subcontract" with local criminal organizations or youth gangs to move product through a particular port of entry, or over a particular land or sea route.

3) While they use violence to protect their products and defend territory, OCGs are not armed groups or insurgencies driven by an ideological agenda to seize control of a government. They have used arms, most of which come from the United States illegally, to protect and/or gain control of routes and territory, as well as intimidate rivals, law enforcement, and the public.

4) They are not static but opportunistic (or pragmatic) organizations with constantly changing alliances. Former "enforcers" break off from their masters to form "independent" groups. As leaders or bosses are killed or captured, underlings compete for control of the organization and seek to form new alliances. At times, once bitter rivals are known to form alliances against a common enemy, or they use their alliance to reduce the cost of doing business.