According to the National Statistics Office (NSO), of the 87,869 household population of the City of Isabela in 2007, there was almost equal distribution of males (49.8 percent) and females (50.2 percent). This translated to a sex ratio of 99 males for every 100 females, the same sex ratio recorded in 2000.

NSO revealed that more than half (56.4 percent) of the household population of the City of Isabela were in the voting age group (18 years old and over). About 50.7 percent of the voting-age population were females while 49.3 percent were males.

Nearly half (47.9 percent) of the household population 10 years old and over in 2007 were married while 44.2 percent were never-married. The marital status of the rest of the population was either widowed, divorced/separated, common law/live-in, or unknown. Among never-married persons, there were more males (52.7 percent) than females (47.3 percent). Females dominated the males in the rest of the categories for marital status, except for common law/live-in category.

In 2000, the proportion of married persons was 47.1 percent, while the proportion of never-married persons was 45.4 percent of the total household population 10 years old and over.

Of the household population 5 years old and over, 35.9 percent had attended or finished elementary education, 25.1 percent had reached high school, 9.4 percent were college undergraduates, and 10.8 percent were academic degree holders.

More than half of those with academic degrees (52.8 percent) were females. However, there were more males (55.2 percent) than females who pursued post baccalaureate studies.

Among household population 5 to 24 years old, approximately three out of five (63.5 percent) attended school at anytime during School Year 2007 to 2008. Of the total females aged 5 to 24 years, 64.3 percent attended school at anytime during the said School Year, while attendance for males was 62.6 percent of the total males aged 5 to 24 years.