This prospective study aimed to identify predictors of intention and subsequent attendance of flexible sigmoidoscopy screening using constructs derived from the Health Belief Model (HBM). A total of 4,330 people aged 54 years and registered at 1 of 83 participating English general practices were sent a preinvitation questionnaire to assess sociodemographics, HBM variables including perceived benefits, barriers, seriousness, health motivation, and external cues to action as well a range of other constructs and personal characteristics known to relate to cancer screening. Of the 1,578 respondents (36.4%), 1,555 (98.5%) answered the intention question: 52.9% stated definitely yes, 38.1% probably yes, 6.8% probably not, and 2.2% definitely not. Intentions were positively associated with a higher score on a scale of benefits (odds ratio [OR] = 4.62; 95% confidence intervals [CI; 3.24, 6.59]) and health motivation, that is, interest in other ways of preventing colorectal cancer (OR = 2.61; 95% CI [1.62, 4.22]), while a higher score on perceived barriers (OR = 0.19; 95% CI [0.12, 0.31]) and currently following recommended healthy lifestyle behaviors (OR = 0.31; 95% CI [0.16, 0.59]) were negatively associated. Attendance was verified for 922 intenders (65.2%) of whom 737 (79.9%) attended. Attendance was predicted by health motivation (OR = 1.75; 95% CI [1.07, 2.86]), perceived benefits (OR = 1.82; 95% CI [1.37, 2.43]), perceived barriers (OR = 0.47; 95% CI [0.32, 0.69]), individual-level deprivation (OR = 0.26; 95% CI [0.14, 0.50]), and having diabetes (OR = 0.48; 95% CI [0.25, 0.94]). This study supported the usefulness of the HBM in predicting cancer screening and was further enhanced by adding non-HBM variables such as individual socioeconomic deprivation and comorbidities. (PsycINFO Database Record (c) 2019 APA, all rights reserved).