Conventional remediation-monitoring programmes, i.e. analysis of contaminant and metabolite concentrations over time and space, often provide inconclusive assessments due to inability to resolve among mixing of several contaminant sources, degradation, dispersion and other redistribution processes. The isoSoil objective is to firmly establish concentration-independent contaminant-specific isotope analysis (CSIA) as a novel, user-friendly and powerful tool for both degradation monitoring and source apportionment of organic contaminants in soil. The balanced isoSoil consortium with world-leading CSIA research groups, progressive remediation-focused and analytical services companies and experienced software enterprises will enable a) applications of multiple CSIA systems (13C/12C, 2H/1H, 15N/14N and 37Cl/35Cl) for improved site-specific characterization and monitoring of microbial and abiotic degradation, b) applications of CSIA “isotopic fingerprinting” (14C/12C, 2H/1H, 37Cl/35Cl, and 81Br/79Br) for source apportionment of both regional diffuse and locally mixed contamination scenarios (i.e., environmental forensics) and, c) emphasis on development and demonstration of web-based commercial software to aid soil managers in sampling and interpretation of CSIA results. The CSIA concept provides a well-defined and improved tool to for assessment and monitoring of the 3.5 mill contaminated soil sites in EU. Application of multi-element CSIA enables enhanced power to resolve between the many co-occurring processes. CSIA-based DEGRADATION MONITORING answers to Call Topic “improved tools for site characterization and monitoring of contaminated soils including chemical analysis”. CSIA-based SOURCE APPORTIONMENT answers to Call Topic “development of tools for detection of local, primary, or secondary sources”.