PURPOSE: To determine which patient and injury factors are associated with the detection of high-grade laxity on examination under anesthesia before anterior cruciate ligament (ACL) reconstruction. METHODS: We identified 2,318 patients who underwent primary ACL reconstruction without associated ligament injuries. Demographic data and information regarding meniscal tears were collected. Patients with high-grade Lachman (difference from contralateral side >10 mm), pivot-shift (International Knee Documentation Committee grade 3+), or anterior drawer (difference from contralateral side >10 mm) tests were identified by physical examination under anesthesia before ACL reconstruction. Logistic regression modeling was used to evaluate whether chronicity of the ACL injury, patient age, sex, body mass index, generalized ligamentous laxity, and presence of meniscal tears were associated with increased odds of high-grade laxity, while we controlled for examining surgeon. RESULTS: Patients with chronic tears (>6 months from injury) had greater than twice the odds of having high-grade Lachman, pivot-shift, and anterior drawer tests (all P < .001) relative to patients with acute tears (<3 months from injury). Generalized ligamentous laxity (odds ratio [OR], 2.33; P < .001) and the presence of medial (OR, 1.63; P < .001) or lateral (OR, 1.41; P = .013) meniscus tears were associated with increased odds of a high-grade Lachman test. Age younger than 20 years (OR, 1.34; P = .023), female sex (OR, 1.49; P = .001), generalized ligamentous laxity (OR, 3.46; P < .001), and the presence of a medial (OR, 1.53; P < .001) or lateral (OR, 1.27; P = .041) meniscus tear were associated with increased odds of a high-grade pivot-shift test. Generalized ligamentous laxity (OR, 2.27; P < .001) and the presence of a medial (OR, 1.73; P = .001) or lateral (OR, 1.50; P = .010) meniscus tear were associated with increased odds of a high-grade anterior drawer test. CONCLUSIONS: Chronic ACL tears, generalized ligamentous laxity, and meniscus tears are associated with increased odds of high-grade laxity with all 3 tests. Female patients and age younger than 20 years are associated with increased odds of a high-grade pivot-shift test. LEVEL OF EVIDENCE: Level II, lesser-quality prospective study.