Background: Bereaved families endure tremendous grief. However, few studies have longitudinally investigated caregivers' bereavement grief for more than one year postloss and none is from family-oriented Asian countries. Objectives: We explored longitudinal changes in and modifiable predictors of severe depressive symptoms for Taiwanese family caregivers of terminally ill cancer patients over the first two years postloss. Design: For this descriptive, longitudinal study, severe depressive symptoms (Center for Epidemiological Studies Depression Scale score ≥16) were measured 1, 3, 6, 13, 18, and 24 months postloss. To identify modifiable factors (preloss depressive symptom levels, subjective caregiving burden, objective caregiving load, preparedness for patient death, and postloss social support) associated with postloss severe depressive symptoms, we used multivariate logistic regression modeling with the generalized estimating equation. Setting/Participants: Bereaved caregivers ( N = 285) were recruited by convenience from a medical center in northern Taiwan. Results: Bereaved family caregivers' prevalence of severe depressive symptoms peaked one month postloss (73.3%) and significantly decreased to 15.2% 24 months after the patient's death. After adjusting for confounders, bereaved caregivers were more likely to have severe depressive symptoms if they had heavy objective caregiving load and higher preloss depressive symptom levels. However, their likelihood of severe depressive symptoms was buffered by being better prepared for the patients' death and having greater social support. Conclusions: Bereaved family caregivers' severe depressive symptoms decreased significantly over the first two years postloss. Healthcare professionals should appropriately assess at-risk bereaved caregivers when patients are still alive and provide effective interventions to facilitate caregivers' return to normal life.