General information
Impact Assessment
What is Impact Assessment?
Impact assessment (IA) is the process of identifying the future consequences of a current or proposed action. It is a key decision-support tool used worldwide to evaluate the environmental, social, health, and economic effects of policies, plans, programs, and projects before decisions are made.
IA can help improve the design and outcomes of initiatives by:
- Encouraging transparency and public participation
- Enhancing sustainability and equity
- Supporting better-informed decisions
IA is used across sectors and regions to promote development that is sustainable, socially responsible, and environmentally sound.
Read on for links to downloadable resources, videos, and more detailed explanations of IA.
Downloadable Resources
📘 FasTips: Impact Assessment (2-page PDF)
Five important things to know and do about IA, ideal for sharing or quick reference.
📘 What is Impact Assessment? (4-page PDF)
A deeper dive into IA’s definition, purpose, legal frameworks, history, and connection to sustainable development.
📘 IAIA’s Resource Library
Your gateway to practical tools, guidance documents, webinars, and publications supporting best practices in IA.
What is impact assessment? (3-minute video)
International delegates at IAIA16 answer: What is IA? Why is it important? How does it connect to sustainable development?
Rationale for doing impact assessment (3-minute video)
IAIA member Bill Ross (Canada) explains why IA is not just a regulatory checkbox but a smart business strategy.
Understanding impact assessment (1-hour video)
IAIA trainer Richard Morgan (New Zealand) gives an introduction to the purpose, principles, and types of IA.
More about Impact Assessment
Introduction to Impact Assessment
Definition and Purpose
Impact assessment (IA) is a structured process for considering the implications for people and their environment of proposed actions, while there is still an opportunity to modify—or, if necessary, abandon—the proposals. IA is applied at all levels of decision-making, from policies to specific projects.
Note on Terminology
Some practitioners of policy analysis use “impact assessment” differently—referring instead to evaluating whether a policy achieved its desired impact. This alternative use, sometimes termed “participatory impact assessment,” is distinct from the approach described on this page.
Evolution of the Concept of IA
Initially, IA was primarily concerned with environmental factors but has since expanded to include a more integrated approach that considers social, economic, and health impacts. This broader understanding reflects the changing priorities in assessing impacts on both natural and human-modified environments.
Core Principles and Objectives of IA
IA aims to:
- Provide decision-makers with comprehensive analyses of the biophysical, social, economic, and institutional consequences of proposed actions.
- Promote transparency and public participation in decision-making.
- Identify methods for monitoring and mitigating adverse impacts.
- Contribute to environmentally sound and sustainable development.
This process benefits proponents, stakeholders, local communities, and decision-makers by ensuring that diverse perspectives—especially those from historically marginalized or disadvantaged communities—are taken into account.
Types of IA
Different forms of IA have emerged to address sector-specific challenges. These include:
- Environmental Impact Assessment (EIA)
- Social Impact Assessment (SIA)
- Health Impact Assessment (HIA)
- Strategic Environmental Assessment (SEA)
- Cultural Heritage Impact Assessment (CHIA)
- Human Rights Impact Assessment (HRIA)
- Gender-Based Analysis / Gender Impact Assessment
- Cumulative Effects Assessment (CEA)
While sharing common principles and methodologies, these forms may vary in their specific methods and techniques.
The need to apply IA at strategic levels (such as policies, legislation, plans, and programs) led to the development of Strategic Environmental Assessment (SEA). SEA is widely recognized in legal frameworks across various jurisdictions, including the European Union’s 2001 directive on environmental assessment. SEA mainstreams environmental, social, economic, and health considerations early in the decision-making process.
In recent years, IA has become strongly linked to sustainability. The integration of sustainability principles into all forms of IA is widely accepted, though some still advocate for a distinct ‘Sustainability Assessment’ framework.
Methodologies and Tools in IA
Effective IA relies on a suite of instruments and tools drawn from both the physical and social sciences, including:
- Impact prediction and forecasting
- Impact evaluation and significance assessment
- Risk assessment and analysis
- Life cycle analysis
The success of IA not only depends on the quality of these analytical methods but also on the follow-up processes that ensure recommendations are implemented and effective.
Regulatory Framework and International Agreements
IA is increasingly recognized in international environmental law and is associated with several key conventions and regulatory instruments:
- The U.S. National Environmental Policy Act (NEPA) and its environmental impact statements (EIS) introduced in 1970.
- International agreements such as the Espoo Convention (1991), the Protocol on SEA (Kiev, 2003), the Ramsar Convention, the UN Convention on the Law of the Seas, and the Antarctic Treaty.
- Regional instruments and conventions on topics ranging from migratory species to cultural heritage and landscape protection.
- Recent international standards, such as the IFC Performance Standards (2012) and updates to the OECD Guidelines for Multinational Enterprises, further reinforce the role of IA in global governance.
These frameworks underscore the importance of IA in guiding environmental and social governance.
Financial and Institutional Support for IA
The practice of IA is supported by a variety of institutions:
- Multilateral Development Banks and the World Bank have progressively strengthened IA and SEA requirements, adapting to evolving global sustainability and social governance standards.
- National Development Assistance Agencies: These organizations use IA to integrate environmental and social considerations into development projects.
- Private Sector Financial Institutions: The adoption of the Equator Principles—now supported by over one hundred financial institutions worldwide—demonstrates the private sector’s commitment to responsible project finance and environmental management.
Conclusion
Impact assessment is an evolving process that plays a crucial role in informed decision-making. By integrating rigorous analysis with participatory approaches, IA not only enhances transparency but also contributes significantly to sustainable development and environmental management.
Special Thanks
Special thanks to Júlio de Jesus, Richard Morgan, and Loreley Fortuny for providing content and editing this original topic information.