Spouses are often the first providers of informal care when their partners develop dementia. We used The National Longitudinal Caregiver Study (NLCS, 4 annual surveys, 1999 to 2002) and identified 3 distinct longitudinal patterns (trajectory classes) of total daily caregiving time provided by the wife to her husband using Generalized growth mixture models (GGMM). About 56.4% of the sample (N=828) was found to have an increase in the trajectory of total daily caregiving time (mean 252 min/d at baseline, rising to 471 min/d at time 4). Four hundred forty-four (30.3%) caregivers had a trajectory described by a moderate increase in caregiving time (an increase from a mean of 464 min/d at baseline to 533 at wave 4), whereas 195 (13.3%) had a sharply declining trajectory (a decline from a mean of 719 min/d at baseline to 421 at wave 4). There was no significant difference in the duration (time since onset) of caregiving at baseline for these 3 trajectories. GGMM are well suited for the identification of distinct trajectory classes. Here they show that there are large differences in caregiving time provided to persons with dementia, who seem to be quite similar.