The evaluation for Celebremos La Salud, a community randomized trial of Hispanic cancer prevention found no differences in mammography screening rates between intervention and control communities. The goal of the present study was to determine reasons for the intervention's lack of effectiveness. In the first aim, we assessed reach of the intervention. In the second, we assessed which intervention activities were associated with mammography use. In the third, we examined whether factors related to health care access, education level, or age modified the effect of the intervention. Data were used from a post-intervention survey of 20 rural communities in Washington State. Hispanic (N = 202) and non-Hispanic White (N = 389) women, over age 40 formed the sample. Reporting having awareness of or having participated in intervention activities was positively associated with Hispanic ethnicity and intervention group and negatively associated with lack of health insurance and having a lower education level. Only one intervention activity was associated with screening use. Having participated in presentations at organizations was positively associated with having had a mammogram in the previous 2 years for Hispanic women. No individual level modifiers influenced the intervention's effectiveness. Heavily targeting the intervention to Hispanic women and not reaching as many White women may have contributed to the lack of intervention effect. Increasing mammography screening rates among women living in a rural area may require improved access to health care and reaching women with lower education levels and lack of health insurance.