The aim of this study is to assess the effect of rural-urban residence and modernization on fertility preference among urban female migrants versus rural female non-migrants. The specific objective is to assess the impact of the amount and timing of urban residential experience on six dimensions of modernism in attitudes and behaviour. A sample of 397 women of the reproductive age living in Mwanza region was interviewed in 2012. Data were collected using structured questionnaires and focus group discussions. Data analysis technique employed was multivariate using SPSS version 16.0 and ethnograph softwares for quantitative and qualitative data respectively. Results show that scores on modernism indices were consistently higher for women with urban residential experience. Women who migrated from villages to the city reported attitudes and behaviours more modern than women with no urban residential experience. The study concludes that the change from traditional to modern values, norms and behaviours among female migrants came from gaining an urban experience. Thus recommending that women’s migration empowerment is crucial to fertility regulation in Tanzania