The paper presents an investigation on the development of energy security level assessment technology. The system of energy security indicators, covering technical, economic and socio-political aspects, is introduced. The security indicator is a special index which gives numerical values to important issues for security of energy sector. In the paper, each indicator is described by presenting the title, comments, factual and threshold, pre-critical and critical state values. The integral characteristics of these indicators show the level of energy security and in order to identify it, a point system assessment scale is used. The methodology developed in this paper is applied for the assessment of the Lithuanian energy security level in different scenarios. At first, indicator groups are constructed and group weights are determined. The weights of indicators within each group are established in two ways: when all weights are equal and one indicator is dominating. Taking into consideration the assessment of indicators by points, their weights in groups and group weights, the Lithuanian energy security level was determined according to separate indicator blocks. The security level of each indicator and each indicator block, and total security level are presented as the results. The indicators that have the highest impact on the security level increase or decrease are determined as well. (C) 2011 Elsevier Ltd. All rights reserved.