Brain growth and structural organization occurs in stages beginning prenatally. Toxicants may impact neurodevelopment differently dependent upon exposure timing and fetal sex. We implemented innovative methodology to identify sensitive windows for the associations between prenatal particulate matter with diameter≤2.5μm (PM2.5) and children's neurodevelopment. We assessed 267 full-term urban children's prenatal daily PM2.5 exposure using a validated satellite-based spatio-temporally resolved prediction model. Outcomes included IQ (WISC-IV), attention (omission errors OEs, commission errors CEs, hit reaction time HRT, and HRT standard error HRT-SE on the Conners' CPT-II), and memory (general memory GM index and its components — verbal VEM and visual VIM memory, and attention-concentration AC indices on the WRAML-2) assessed at age 6.5±0.98years. To identify the role of exposure timing, we used distributed lag models to examine associations between weekly prenatal PM2.5 exposure and neurodevelopment. Sex-specific associations were also examined. Mothers were primarily minorities (60% Hispanic, 25% black); 69% had ≤12years of education. Adjusting for maternal age, education, race, and smoking, we found associations between higher PM2.5 levels at 31–38weeks with lower IQ, at 20–26weeks gestation with increased OEs, at 32–36weeks with slower HRT, and at 22–40weeks with increased HRT-SE among boys, while significant associations were found in memory domains in girls (higher PM2.5 exposure at 18–26weeks with reduced VIM, at 12–20weeks with reduced GM). Increased PM2.5 exposure in specific prenatal windows may be associated with poorer function across memory and attention domains with variable associations based on sex. Refined determination of time window- and sex-specific associations may enhance insight into underlying mechanisms and identification of vulnerable subgroups. •We used data-driven methods to objectively examine sensitive windows of prenatal PM2.5 on childhood neurodevelopment.•Our findings suggested sex-specific, time-dependent associations that may vary dependent on different cognitive domains.•A more definitive understanding of such sex-specific temporal associations may provide insights into underlying mechanisms.