Frontotemporal lobar degeneration (FTLD) often presents with asymmetric atrophy. We assessed whether premorbid occupations in FTLD patients were associated with these hemispheric asymmetries. In a multi-center chart review of 588 patients, occupation information was related to location of tissue loss or dysfunction. Patients with atrophy lateralized to the right had professions more dependent on verbal abilities than patients with left-lateralized or symmetrical atrophy. In a subgroup of 96 well-characterized patients with quantified neuroimaging data, the lateralization effect was localized to the temporal lobes and included verbal and mathematical ability. Patients whose professions placed high demands on language and mathematics had relatively preserved left temporal relative to right temporal volumes. Thus, occupation selection occurring in early adulthood is related to lateralized brain asymmetry in patients who develop FTLD decades later in the relatively deficient hemisphere. The finding suggests that verbal and mathematical occupations may have been pursued due to developmental right-lateralized functional impairment that precedes the neurodegenerative process. Alternatively, long-term engagement of activities associated with these occupations contributed to left-lateralized reserve, right-lateralized dysfunction, or both.