: This paper aims to analyze usage rates for the emergency contraceptive pill (ECP) among women living in the city of São Paulo and their associated factors.

: A population based cross-sectional survey was conducted in 2015 with a probabilistic sample of 4,000 women aged 15-44 living in São Paulo, Brazil. Response rate for households was 75% and 77% for eligible women. Binary logistic regression models were used to describe the association between each outcome and selected variables.

: 51.4% of women living in the city of São Paulo had used ECP at least once in their lifetime. Women under 35 were more likely to use ECP, as were those with more than 9 years of schooling, having at least one live birth, not cohabiting with a partner, with more than two lifetime sexual partners and as length of sexual life decreased. Among ECP users, 32.6% used it only once, 47.5% used it 2-4 times, and 19.9% used it 5 or more times.

: Our findings suggest that ECPs have been incorporated into the contraceptive method mix for many women as a fundamental strategy for regulating fertility. Particularly young women, unmarried women and those who have had more partners seem to take greater advantage of ECP to prevent pregnancy.

: Despite the high use rate, lower levels of schooling are associated with lower levels of ECP use. There is a need for both policies to reduce schooling inequities and strategies to improve women's knowledge of reproduction and contraception.