This study aims to clarify the effect of career capital on the sustainable competitive advantage when human resource management’s capabilities work as a mediator variable in construction companies specializing in concrete in Amman. The total number of companies are (23), the companies that showed cooperation and filled out the questionnaire were (17) companies. The study population consisted of (1400) employees from various administrative levels. Applying the study to the whole study population is difficult due to its large size; thus, a simple random sampling method is used. (302) questionnaires were distributed, the retrieved questionnaires valid for analysis were (250) and constituted of (83%). The unstructured interviews were adopted to define the study problem in the construction companies specialized in concrete. The questionnaire is the tool for measuring the study variables by collecting data and then analyzing those using descriptive and inferential statistics. The most important study results are that in the construction companies specialized in concrete industries in Amman; the level of career capital was high, and the level of sustainable competitive advantage was medium. At the same time, the results showed that the level of human resource management capabilities was high. The results also indicate that human resource management's capabilities partially mediate the impact of career capital and the sustainable competitive advantage. Human resource management's capabilities contributed to increasing this impact; this means that human resources management's capabilities play an essential role in activating the relationship between career capital and sustainable competitive advantage.