Dogs vary considerably in physical and behavioural characteristics, due to selective breeding aimed at creating dogs suitable for various working roles. Nowadays, few dogs undertake this work. Instead, most are kept as human companions. Not all dogs are equally suited to this role, with thousands being admitted to shelters because they display behaviour deemed inappropriate by owners. To identify traits considered important in companion dogs, 877 volunteers (79.8% female) aged 18 to 82 years (mean = 34.3, SD = 14.5) completed a survey about their 'ideal' dog. Characteristics identified as important included the dog being medium sized, short haired, desexed, safe with children, housetrained, healthy, obedient, friendly and affectionate. Desirable behaviours were grouped using Principal Component Analysis into five factors; calm/compliant (CC), sociable/healthy (SH), energetic/faithful/protective (EFP), socially acceptable (SA), and non-aggressive (NA), which explained 45.7% of the total variance. Pearson's correlation coefficients indicated that scores on the CC scale were moderately positively associated with participants' age (r = 0.28, n = 874, P<0.01). EFP scores were weakly negatively associated with participants' age (r = - 0.12, n = 874, P<0.01) and education level (r = - 0.18, n = 877, P<0.01). Women preferred a dog who is CC [t(870) = -2.33, P = 0.02], SH [t(870) = -2.57, P = 0.01] and NA [t(870) = -2.67, P = 0.008] while men preferred one which is EFP [t(870) = 3.09, P = 0.002]. Non-dog owners rated the EFP factor [t(874) = 2.65, P = 0.008] as more important than did dog owners. Overall, there was a preference for dogs that might be described as amicable. This is important because it means that breeders and trainers can make more informed selection and management decisions, potentially increasing owner satisfaction, reducing the incidence of problem behaviours exhibited by dogs and improving dog welfare.