The concept of the National Integrity System (NIS) has been developed and promoted by TI as part of its holistic approach to countering corruption. While there is no blueprint for an effective system to prevent corruption, there is a growing international consensus as to the salient features of anti-corruption systems that work best.

The NIS consists of the key institutions, laws and practices that contribute to integrity, transparency and accountability in a society. When it functions properly, the NIS combats corruption as part of the larger struggle against abuse of power, malfeasance, and misappropriation in all its forms. The NIS approach provides a framework with which to analyse both the extent and causes of corruption in a given national context, as well as the adequacy and effectiveness of national anti-corruption efforts. By diagnosing the strengths and weaknesses of a particular integrity system, an evaluation based on the NIS can help inform anti-corruption advocacy and reform efforts.

The main ‘pillars’ of the NIS are considered to be the following:

· Executive
· Legislature
· Political Parties
· Electoral Commissions
· Supreme Audit Institution
· Judiciary
· Public Sector
· Police and Prosecutors
· Public Procurement
· Ombudsman
· Anti-corruption agencies
· Media
· Civil Society
· Private Sector
· Regional and Local Government
· International Institutions

The NIS approach underpins many aspects of TI’s work, including much of the national and international advocacy undertaken by the TI movement. It also provides the conceptual basis for many TI publications, including the TI Source Book, the Anti-Corruption Handbook: National Integrity Systems in Practice and the NIS Country Study series.

The TI Source Book argues the case for a systematic approach to curbing corruption across all sectors of society. It introduces the concept of the 'National Integrity System', providing a framework with which to analyse both the causes of corruption and the effectiveness of anti-corruption reform in a given national context. The TI Source Book is widely cited as a groundbreaking document in the anti-corruption movement and has been translated into more than 20 languages. Its last release as an English-language print publication was in the year 2000. In September 2005, TI launched an adaptation entitled ‘TI Source Book: The Arab Integrity System’, which seeks to address the causes and consequences of corruption in the Arab context.

The TI Anti-Corruption Handbook (ACH) is a practical, online guide which aims to assist the process of designing and applying anti-corruption measures – from legal reform to institution-building. Intended as a one-stop reference for practitioners around the world, it provides a unique and up-to-date overview of key reform elements, developing guidelines for their effective implementation illustrated by examples of good practice. The ACH is based on TI’s National Integrity System approach to countering corruption. It seeks to build on this approach by addressing the key elements of anti-corruption reform in a useful and practical way. Though it retains a substantial focus on anti-corruption systems in the public sector, the ACH also assesses the role of non-governmental actors and inter-governmental bodies in combating corruption. By covering public and private spheres of governance, the ACH reflects recent thinking about the broadened context in which policy-making takes place.

TI’s National Integrity System (NIS) country studies are qualitative reports that provide a detailed and nuanced assessment of anti-corruption systems at country level. Via these studies, TI aims to provide an overview of the National Integrity Systems in countries from all regions of the world. The studies provide both benchmarks for measuring further developments in these countries, and a basis for comparison among countries. TI believes it is necessary to understand the provision for and capacity of National Integrity Systems to be able to diagnose corruption risks.

The NIS country studies are an important tool that complement TI’s global indices and surveys (such as the Corruption Perceptions Index, Bribe Payers Index, and Global Corruption Barometer). By exploring the specific practices and constraints within countries, they create a strong empirical basis upon which to promote better governance across all aspects of a particular society and enable the formulation of targeted and effective national anti-corruption reforms. NIS Country Studies are unique in the anti-corruption field, with more than 50 such studies conducted since 2001.