To derive a comprehensive understanding on the potential health risks associated with exposure to engineered nanomaterials (ENMs), a detailed understanding of the physical and chemical characteristics of the ENMs is critical. The majority of the published literature on the biological responses to ENMs does not provide detailed physicochemical characterization data to identify which of the material?s characteristics are critical to observed biological responses. The effects of subtle changes in the physicochemical properties of ENMs (such as size, charge, hydrophobicity, surface chemistry, etc.) on the biological response are therefore largely unknown. A new $35M (over five years) research program (NIEHS Centers for Nanotechnology Health Implications Research, [NCNHIR]) established in 2010 is focused on developing an understanding of how physicochemical characteristics of ENMs influence their interactions with biological matrices at the cell, molecular and organ level, and how this information can be integrated to develop predictive modeling systems to assess potential health effects. The NCNHIR formed a consortium and the investigators will be working with a common set of ENMs along with project?s proposed in their research plan. To facilitate access to these grantees and to get a standardized physicochemical characteristics data for the ENMs to be studied by this consortium NIEHS established a contract with Nanotechnology Characterization Laboratory (NCL) at NCI/SAIC Fredrick.