Particular aspects confirm the existence of a CpG island methylator phenotype (CIMP) in colorectal cancer, and provide novel validated DNA methylation markers associated with CIMP. Additional aspects provide novel methods and compositions for: determining CIMP status in colorectal cancers, determining the relationship between CIMP status and other molecular features of the cancers (e.g., BRAF mutation, KRAS mutation and MSI status); determining the relationship between CIMP status and other variables (e.g., age, sex, tumor location, family history, race, country of origin, tumor characteristics (including, tumor type, tumor grade, invasive margin characteristics, lymphocyte infiltration characteristics, direct spread, lymph node spread, venous spread and type of residual adjacent polyp, if present)); and determining, between subgroups defined by CIMP status and BRAF mutations, effects of selected risk factors (e.g., body mass index, smoking history, alcohol intake, dietary folate intake, folate metabolic enzyme polymorphisms and history of hormonal use).