Along with Latvia’s integration into Europe’s common economic area and with the development of environmental awareness into society, the environmental issues have become more important both in the sphere of social politics and economics. The state has taken on responsibility for ensuring the sustainability of nature and environment which is proved by national legislation. Good practice has been implemented and tested – environmental impact assessment (EIA) of new business ideas and projects before putting into realization at their earliest stage. Since the law „On the environmental impact assessment” has entered into force in 1998, 99 projects in different spheres of economic activity have been carried out, the main ones being the traffic infrastructure, the development of agricultural complexes and production units and mining industry. Every kind of economic activity has an influence upon environment, therefore it is important to assess the significance of these impacts adequately and impartially, consequently the decision maker is provided with precise information and assessment results. The goal of EIA is to assess in due time the possible impact upon environment, nature and social-economic conditions that may result from the planned activity in order to carry out activities of prevention and reduction at possibly earliest stage of project development. The indicators ensure the quantitative environmental assessment of planned activities which provide the highest possible impartiality in assessment procedure. Up till now, the selection of indicators for EIA has been left to the choice of the applicant. The team of experts involved in each project carries out EIA according to assessment program by their own method, level of expertise and obligations towards the applicant. Consequently, there is not unified indicator system, for example, environmental assessment of motor roads, agricultural complex, etc. In order to avoid superficial and biased approach in EIA, as it is judged from the experience of many countries, it is necessary to approve the set of indicators for each sphere of environment. The lack of indicator validation or validation may cause negative reference on the quality of environmental and social impact assessment, usefulness and credibility, i.e., to discredit or question the results of EIA. The necessity of approved indicator system is higher in those countries, where the applicant has to pay for EIA, as it is in Latvia. There are well –known and elaborated several indicator validation or validation methods that are quite easily perceivable and usable. There are certain criteria both for indicators and their validation. Indicator is considered to be approved if it is scientifically acknowledged, its information is appropriate and it is available and utilized by end users. Indicators are selected for each goal or problem in particular sphere and they have to be understandable, easily measurable, clearly reflect the changes in environment and scientifically acknowledged. The methods for indicator assessment and validation can be combined as it is indicated in several literature sources. The goal of the paper is to establish optimal indicator system for environmental impact assessment that would be suitable for Latvia. Therefore, one of the tasks is to examine the existing indicator validation methods, identify simple, quite easily usable indicator validation method and to adopt it. The validation procedure, in general, consists of establishment of indicators, validation criteria, validation scheme and adoption. In this phase of work, the existing validation methods are evaluated in practical examples along with their comparisons. The results obtained in practical application of different methods will provide for more detailed research in quality strengthening of EIA in Latvia.