Recent research has found that men and women who end up in gambling treatment tend to follow different trajectories to that endpoint: women generally begin gambling later in life, but progress to problems and seek treatment more quickly. With women's prevalence rates of gambling and disordered gambling increasing, it has become important to identify the causes and consequences of these trajectory differences. The current study used a sample of 2,256 gamblers enrolled in the Iowa Gambling Treatment Program to examine the relationship of gender and other demographic, economic and health-related (i.e., psychosocial) factors to empirically-identified gambling problem trajectories. The results indicated that gender made a statistically significant contribution to the prediction of trajectory, but increased predictive accuracy by only 1-2% beyond a model with psychosocial predictors. Gender's contribution was limited to its relationship to age of initiation; men and women's problem progression did not differ meaningfully once age of gambling initiation was taken into account. Gender is a unique contributor to the development of gambling problems among treatment seekers, but it is only one small part of the myriad psychosocial characteristics that influence gambling problem development.