Environmental Impact Assessment (EIA) is a long-standing, well developed form of impact assessment. It was developed in the 1960s with the aim of systematically incorporating environmental concerns into decision making. According to the United Nations Environment Programme (UNEP), EIA is a tool used to identify the environmental, social and economic impacts of a project prior to decision-making. It aims to predict environmental impacts at an early stage in project planning and design; to find ways and means to reduce adverse impacts; to shape projects to suit the local environment; and to present the predictions and options to decision-makers. By using EIA both environmental and economic benefits can be achieved. These include reduced cost and time of project implementation and design; avoided treatment/clean-up costs; and impacts of laws and regulations.

Strategic Environmental Assessment (SEA) is linked to Environmental Impact Assessment. However it aims to develop environmental assessments for more strategic decision making, such as the development of plans and programmes.

According to Nilsson & Dalkmann (Nilsson, M. and H. Dalkmann. 2001. Decision-making and strategic environmental assessment, Journal of Environmental Assessment Policy and Management (3) 3), SEA aims to incorporate environmental and sustainability considerations into strategic decision making processes such as the formulation of policies, plans and programmes.  

Partidario & Clark (Partidário, MR. and R. Clark. 2000. Perspectives on Strategic Environmental Assessment. New York, Lewis) define SEA as a 'systematic, on-going process for evaluating, at the earliest appropriate stage of publicly accountable decision making, the environmental quality, and consequences, of alternative visions and development intentions incorporated in policy, planning, or programme initiatives, ensuring full integration of relevant biophysical, economic, social and political consideration'.

Social Impact Assessment (SIA) is 'the process of assessing and managing the impacts of a project, plan, program or policy on people,' according to Vanclay (Vanclay, F, 2003. International principles for social impact assessment. Impact Assessment and Project Appraisal  21 1, pp. 5–11). It is an overarching framework for the evaluation of all impacts on humans, and it looks at how people and communities interact with their socio-cultural, economic and biophysical surroundings. SIA includes the processes of analysing, monitoring and managing the intended and unintended social consequences (both positive and negative) of planned interventions, and any social change processes invoked by those interventions. Its primary purpose is "to bring about a more sustainable and equitable biophysical and human environment" (Vanclay, 2003 - International Principles For Social Impact Assessment). Social Impact Assessment assumes that social, economic and biophysical impacts are interconnected. It can be applied in different contexts and for different purposes, and it can be ex ante as well as ex post

An example of Social Impact Assessment is an assessment of the social impacts of disasters.

Health Impact Assessment (HIA)

The World Health Organisation (WHO) defines Health Impact Assessment (HIA) as a combination of procedures, methods and tools by which a policy, programme or project may be judged as to its potential effects on the health of a population and the distribution of those effects within the population. It assesses the health effects of interventions that are not primarily aimed at effecting health, and tries to make policies, programmes and projects health conscious.

The European Commission has developed an impact assessment process which is used in a wide range of areas to assess the economic, environmental and social impacts of policy proposals. It aims to improve the quality of EC proposals, taking into account their side effects, and to improve and simplify the regulatory environment. It also aimsto achieve more consistency between policies and to contribute to sustainable development.

The EC started to develop an integrated impact assessment process to replace all their previous impact assessment mechanisms in 2002, and in 2005 it published a set of guidelines on impact assessment. Their approach to IA consists of six analytical steps and requires stakeholder participation throughout the whole process.

The EC guidelines were updated in March 2006.

Project Cycle Management (PCM) is the term given to the process of planning and managing projects, programmes and organisations. It is used widely in the business sector and is increasingly being used by development organisations. Typically PCM involves the following stages: Programming / Identification / Appraisal / Financing / Implementation / Evaluation, with the findings from Evaluation typically feeding back into the Identification phase. This ensures the cyclic approach of Plan – Do – Check/Feedback – Adapt.

PCM uses tools such as needs assessment, stakeholder analysis, logical framework matrix, problem analysis and so on. These tools are the same as are used for human rights impact assessment.