Sessile serrated adenomas (SSAs) are precursors of 15% to 30% of colorectal cancers but are frequently underdiagnosed. We sought to measure the SSA detection rate (SDR) and predictors of SSA detection after educational training for community gastroenterologists and pathologists. Colonoscopy and pathology data (2010-2014) from 3 medical centers at Kaiser Permanente Northern California were accessed electronically. Gastroenterologists and pathologists attended a training session on SSA diagnosis in 2012. Mean SDRs and patient-level predictors of SSA detection post-training (2013-2014) were investigated. Mean SDRs increased from .6% in 2010-2012 to 3.7% in 2013-2014. The increase in the detection of proximal SSAs was accompanied by a decrease in the detection of proximal hyperplastic polyps (HPs). Among 34,161 colonoscopies performed in 2013 to 2014, SDRs for screening, fecal immunochemical test positivity, surveillance, and diagnostic indication were 4.2%, 4.5%, 4.9%, and 3.0%, respectively. SSA detection was lower among Asians (adjusted odds ratio [aOR], .46; 95% confidence interval [CI], .31-.69) and Hispanics (aOR, .59; 95% CI, .36-.95) compared with non-Hispanic whites and higher among patients with synchronous conventional adenoma (aOR, 1.46; 95% CI, 1.15-1.86), HP (aOR, 1.74; 95% CI, 1.30-2.34), and current smokers (aOR, 1.78; 95% CI, 1.17-2.72). SDRs varied widely among experienced gastroenterologists, even after training (1.1%-8.1%). There was a moderately strong correlation between adenoma detection rate (ADR) and SDR for any SSA (r = .64, P = .0003) and for right-sided SSAs (r = .71, P < .0001). Educational training significantly increased the detection of SSA, but a wide variation in SDR remained across gastroenterologists. SSA detection was inversely associated with Asian and Hispanic race/ethnicity and positively associated with the presence of conventional adenoma, HP, and current smoking. There was a moderately strong correlation between ADR and SDR.