The National Institute of Environmental Health Sciences (NIEHS), part of the Department of Health and Human Services, is seeking proposals for a federal contract focused on the assessment of immunotoxicity through in vitro and in vivo evaluation of immune function. The objective is to provide comprehensive research services to evaluate how selected test agents may modulate immune responses, utilizing both established and innovative methodologies to reduce animal use in toxicology studies. This contract, anticipated to be a cost-plus-fixed-fee type, is expected to be awarded by September 2025, with a base period of one year and nine optional one-year extensions. Interested parties should direct inquiries to Adam Muhsin at adam.muhsin@nih.gov and monitor the Sam.gov website for the solicitation release, which is expected no sooner than 15 days from this notice.