Studies provide inconclusive results on the question whether loss of mental wellbeing is actually associated with decline in physical function in amyotrophic lateral sclerosis (ALS). The purpose of this study was to determine predictors of mental wellbeing in ALS.In total, n = 330 ALS patients were interviewed on parameters of mental wellbeing to evaluate the patients' capacity of psychosocial adaptation. These parameters were global and subjective quality of life (QoL), and depressiveness. A subsample of n = 82 ALS patients were interviewed again within approximately a year (mean 14.34 ± 5.53 months).Both global and subjective QoL were stable, whereas depressiveness increased within the course of 1 year after diagnosis. Physical function decline was associated with mental wellbeing. Progression of physical disabilities and symptom duration were significant predictors of wellbeing in the sense that fast progression and short time since symptom onset (both indicating short time to adapt) were associated with low wellbeing.There is evidence for subsamples in ALS with regard to mental wellbeing, which are mainly determined by clinical parameters. Those subjects being reported in the literature to present with high mental wellbeing are often long survivors. High progression rate and low physical function when attending the clinic for the first time should be red flags and need special attention in clinical counseling.