This EMBO Practical Course on "Deciphering tumour heterogeneity and evolution by integration of multi-omics data" aims to provide practical insights for cancer researchers regarding the potentials and challenges of using high throughput sequencing to estimate intra-tumoral diversity in its multiple facets. The course will start by covering advanced topics in the determination of somatic variants (single nucleotide and structural variants), focusing on the practical challenges of the process. This will include the detection of mutational patterns, selection pressures and driver mutations. Using this as a prior, the course will then focus on techniques for the determination of subclonal diversity and clonal evolution in tumour compared to normal tissue, and its impact on disease outcome. The course will explore techniques to infer the immunogenic potential of a tumour and its impact on tumour evolution, by the integration of genetic and transcriptomic data. We will end by delving into novel single-cell multi-omic techniques to explore intra-tumour diversity and evolution. Participants will have extensive hands-on practice with state-of-the-art techniques discussed in the course, and discussions between lecturers and participants will be actively promoted to enable participants to use novel techniques to enhance their projects.