PMBOK (2004 3rd 英) P292关于合同变更控制系统中提到了争议解决程序，但是没有详细展开。http://www.venables.co.uk/adr.htm 给出了一些概念和解释：

Alternative Dispute Resolution (ADR) was introduced in the 1980s for the resolution of commercial disputes. The advantages of ADR techniques were quickly recognised and judges, following the Civil Procedure Rules in 1999, have discretion to direct the parties to enter into ADR.

Mediation is the most common form of ADR and the service offers the opportunity for a fresh approach to negotiations and to reduce the cost of conflict in time and money. Flexibility and confidentiality are important features.

Arbitration is a binding method of dispute resolution governed by statute. The appointed arbitrator considers the evidence presented by both parties and then issues an award, which is enforceable by the courts.

Adjudication is a process for the early, fast, summary, temporarily binding but interim resolution of disputes, which now applies compulsorily to most construction contracts.

Private inquires may be instigated to defuse problems encountered by organisations such as customer complaints, harassment or discrimination against staff or external threats to investigate services.

Arbitration has been a traditional alternative to court-based litigation. It has been widely used in commercial disputes, particularly those involving international disputes and matters where technical expertise on the part of the decision maker is important. Arbitrators make decisions which bind the parties to the dispute. Procedures used in arbitration can range from informal to rules which essentially mirror court procedures. The benefits of arbitration include its confidentiality, flexibility, speed and the expertise of many arbitrators. It is usually, but not always, cheaper than court.

Conciliation is an established feature of industrial relations. The conciliator brings the parties together and acts as a facilitator in their discussions. The conciliator is not a decision-maker.

Mediation has emerged in the nineties as an increasingly popular form of dispute resolution. Like conciliation, it involves a third party neutral working with the parties to a dispute to facilitate their negotiations more effectively so that they can arrive at a mutually acceptable settlement.

The mediator will assist the parties in exploring options and measuring the strengths and weaknesses of their respective cases. Mediation can save time and reduce the cost of resolving a dispute, both financial and emotional. Mediation can also assist the parties to re-establish trust and respect and can help prevent damage to ongoing relationships. Mediation works best when it is voluntary, although there are some examples of mandatory mediation projects where parties to a dispute are required to go through a mediation process as a prerequisite to being able to seek adjudication of a dispute by a judge or an arbitrator.

Med-Arb is a process in which the parties proceed through a facilitative mediation process and if the matter does not resolve completely or if certain issues remain unresolved following the mediation process, the mediator is entitled to decide the issues as an arbitrator.

Mini Trial is a process which can be useful to companies in dispute in complex matters. Typically, the senior executives of the companies, with authority to settle, form a panel together with one of our members as a neutral Chair of the panel. The legal representatives for both parties make a presentation of their case in a summary fashion, without witnesses or with a minimal number of witnesses. The presentation should include relevant evidence followed by argument. The executives thereby have the opportunity of assessing the strengths and weaknesses of their case and that of the opponent. Following the presentation, the executives negotiate with each other, with or without the assistance of the neutral, attempting to find a mutually acceptable resolution of the issues. The neutral can function in a facilitative mediation manner to explore the issues, needs and concerns of the parties or alternatively, be evaluative and provide a view of the issues for consideration by the parties. This process is non-binding and without prejudice to legal rights.

Neutral Evaluation is a process by which a neutral hears submissions from the parties on the merits of a case and offers a non-binding evaluation of the likely outcome in the event the matter proceeds to adjudication by a judge or an arbitrator.