As an operational definition for the working model of the psychological immune system, the Psychological Immune Competence Inventory (PICI) was developed. The process of instrument construction and studies of the psychometric properties of the inventory will now be presented. In the first step of the instrument construction, operational definitions of the proposed constructs were made. These operational definitions for the 16 constructs were derived through the following procedure. A bank of items sampling each domain of protective factors was obtained. Books, articles and different instruments were scanned to collect inventory items which, according to their content, were associated with the constructs of the psychological immune system model. Taking the operational definition of the 16 psychological immune system constructs as general criteria and using the content of the collected item bank, 250 simple statements were formulated as the initial item set of the PICI. Based on their face validity, the eight most descriptive items for each concept were retained. For replying to the 128 items in the original questionnaire. the respondent had a 4-choice answer scale at his or her disposal, ranging from complete disagreement (l = very false for me) to complete agreement (4 = very true for me). The 128-item bank was continuously revised in a series of studies in which items were produced, administered to several groups and then omitted if they did not have desirable characteristics in terms of reliability analyses. The 8-item format for each scale was subsequently reduced to 5 items per construct. The latest version of PICI has 80 items, (16 scales, each with 5 items) (see Appendix 1). All results presented here were obtained with this version of the PICI. The reader should be aware that the data presented in this study refer to self-reports. Hence, associations with our measures and other, self-report measures will contain common method variance which inflate the correlations to an unknown extent. Findings utilizing criterion measures independent of self-reports will be reported in forthcoming studies.