CACI International Inc, is an American multinational professional services and information technology company headquartered in Arlington, Virginia, United States. CACI provides services to many branches of the federal government including defense, homeland security, intelligence, and healthcare.

CACI has approximately 19,000 employees worldwide.

CACI is a member of the Fortune 1000 Largest Companies, the Russell 2000 index, and the S&P SmallCap 600 Index.

CACI was founded by Herb Karr and Harry Markowitz, who left RAND Corporation in 1962 to commercialize the SIMSCRIPT simulation programming language. The company went public in 1968. "CACI," which was originally an acronym for "California Analysis Center, Incorporated," was changed to stand for "Consolidated Analysis Center, Incorporated" in 1967. In 1973, the acronym alone was adopted as the firm's official name; reflecting the name customers had grown familiar with. In 1975 CACI Limited was founded in the UK.

On June 9, 2004, a group of 256 Iraqis sued CACI International and Titan Corporation (now L-3 Services, part of L-3 Communications) in U.S. federal court. The plaintiffs, former prisoners, allege that the companies directed and participated in torture, war crimes, crimes against humanity, sexual assault, as well as cruel, inhuman and degrading treatment at Abu Ghraib prison. The U.S. Government had hired CACI and Titan to provide interrogation and translation services at military prisons in Iraq.

CACI employees Joe Ryan and Steven Stephanowicz were investigated in the Taguba inquiry. The Department of the Army found that "contractors were involved in 36 percent of the [Abu Ghraib] proven incidents" and identified 6 employees as "individually culpable", although none have faced prosecution, unlike Department of Defense servicemen.

According to an early Army report, a CACI interrogator "[m]ade a false statement to the investigation team regarding the locations of his interrogations, the activities during his interrogations, and his knowledge of abuses". Further, investigators found the CACI interrogator encouraged Military Policemen to terrorize inmates, and "clearly knew his instructions equated to physical abuse".

CACI said only "a small portion" of its employees in Iraq worked as interrogators and none had been criminally indicted "for any misconduct in connection with this work".

On August 26, 2005, Randi Rhodes, a host for the Air America talk radio program, claimed that employees of CACI International had raped and murdered Iraqi civilians at the Abu Ghraib prison. CACI sued Air America and its parent company, Piquant LLC, for allegedly making "false and defamatory" charges. CACI sought $1M in compensatory damages and $10M in punitive damages. The claim was dismissed by a US District Court judge on September 21, 2006. CACI pursued an appeal, having received permission to do so from a bankruptcy court (which lifted the automatic stay that resulted when Air America filed for bankruptcy protection).

In May 2008, four former Abu Ghraib prison inmates, who were all released without charge, brought separate lawsuits in four US courts against CACI and L-3 Communications as well as against three civilians. One of these former inmates, Emad al-Janabi, sued L-3 and CACI for allowing their employees to abuse him physically and mentally at the prison. In a statement released on their website CACI has stated that these lawsuits are "baseless" and they "reject emphatically this latest plaintiff's allegations and claims" calling on "numerous and thorough government investigations" in these allegations.

On March 19, 2009, US District Judge Gerald Bruce rejected claims by CACI that it could not be sued because its interrogators were performing duties prescribed by the contract with the US government. CACI responded that it vowed to "pursue all of its legal alternatives to defend itself and vindicate the company's good name" and that "From day one, CACI has rejected the outrageous allegations against the company in this lawsuit and continues to do so."

On September 11, 2009, the U.S. Court of Appeals ruled that CACI did in fact fall under US military chain of command and thus had government contractor immunity. In October 2010, the U.S. Supreme Court considered hearing an appeal and requested the views of the U.S. Solicitor General on the case. In the meantime, CACI and L-3 continued to argue in federal appellate court for civil immunity, as clients of the federal government in national defense.

In June 2013, the suit was dismissed by a federal judge due to lack of jurisdiction. Plaintiffs vowed to appeal the verdict, which was described as "troubling" by Noah Feldman, a professor at Harvard Law School.

In August 2013, CACI sued the former Abu Ghraib prison inmates for legal expenses related to the dismissed suit. Maxwell O. Chibundu, a law professor at the University of Maryland Francis King Carey School of Law, expressed his surprise at the decision to sue the inmates.

The U.S. Court of Appeals for the 4th Circuit found that the lower court had erred in the June 2013 dismissal, as it lacked jurisdiction to hear the case because the alleged incidents occurred overseas. The case will be returned to the U.S. District Court in Alexandria, Virginia, who had originally dismissed it in June 2013.