Purpose: Tumor-only genomic testing can uncover somatic and germline pathogenic variants (P/LPs) in cancer predisposition genes. We describe the prevalence of P/LPs in BRCA1/2 and PALB2 (B1B2P2) across malignancies and the frequency of clinical germline testing (CGT) in patients with P/LPs in B1B2P2 identified on tumor-only testing. Experimental Design: Among 7,575 cancer patients tested between 2016–2018 with the OncoPanel tumor-only sequencing assay, we characterized P/LP frequencies by tumor type, receipt of CGT prior to or within 12 months (m) after OncoPanel, and factors associated with CGT. Results: 272 (3.6%) patients had OncoPanel-detected P/LPs in B1B2P2 : 37.5% of P/LPs were in BRCA-related cancers; the remainder were in non-BRCA tumors. P/LPs were detected in ≥5% of breast, pancreatic, prostate, ovarian, non-melanoma skin, endometrial, small-cell lung and colorectal cancers. 37.9% of patients with P/LPs received GCT prior to OncoPanel; an additional 10.7% underwent CGT within 12m of OncoPanel. Among 132 with CGT, 88.6% had ≥1 clinical factor for CGT compared to 47.1% who did not undergo CGT. Patients with BRCA -tumors were more likely to have CGT compared to those without (81.4% vs. 29.0%, p<0.0001). Among patients with CGT, 70.5% (93/132) of P/LPs were germline. Conclusions: Tumor-only genomic testing identified P/LPs in B1B2P2 in 3.6% of patients. 52.9% of patients with tumor-detected P/LPs and without CGT did not meet personal or family history criteria for CGT. Additionally, some patients with tumor-detected P/LPs were not referred for CGT, especially those with non-BRCA tumors. Given implications for treatment selection and familial cancer risk, processes to reliably trigger CGT from tumor-genomic findings are needed.