The multitarget stool DNA (mt-sDNA) assay is a noninvasive average-risk colorectal cancer (CRC) screening test. A new biomarker panel was developed for a next-generation test to improve specificity while maintaining/increasing sensitivity. We aimed first to establish an algorithm and cutoff for the next-generation mt-sDNA test and then to validate it using archived samples from the pivotal DeeP-C study (NCT01397747) of the first-generation test.Algorithm development and cross-validation included 3011 samples from 2 specimen collection studies (NCT03821948 and NCT03789162). The algorithm and cutoff were locked before validation. Validation test set samples included 57 CRC, 583 advanced precancerous lesions (APLs), and 7022 samples negative for CRC or APLs from the DeeP-C study, which prospectively enrolled average-risk, asymptomatic adults aged 50-84 years before screening colonoscopy. Next-generation biomarkers included methylated DNA markers ceramide synthase 4 gene, leucine-rich repeat-containing protein 4 gene, serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit gamma isoform gene, and zinc finger DHHC-type containing 1 gene (reference marker), and fecal hemoglobin. Primary validation end points were CRC sensitivity and specificity for the absence of advanced neoplasia. Secondary end points included APL sensitivity and specificity for non-neoplastic findings or negative colonoscopy.Cross-validation and best-fit results from algorithm development closely matched, confirming algorithm reliability and reproducibility. For the test set, next-generation mt-sDNA test sensitivity was 93.0% (95% confidence interval [CI], 83.0%-98.1%) for CRC and 48.4% (95% CI, 44.2%-52.5%) for APLs. Specificity was 88.5% (95% CI, 87.7%-89.2%) for the absence of advanced neoplasia and 90.4% (95% CI, 89.5%-91.2%) for the combination of non-neoplastic findings or negative colonoscopy.Based on archived samples, the next-generation mt-sDNA test demonstrated promising CRC screening performance characteristics that will be further assessed in a prospective clinical validation study (BLUE-C; NCT04144738).