Various types of demographic data can be collected in the field: population censuses, capture–mark–recapture data, and so on. These data sources share common demographic information about the studied population. Bayesian integrated population models (IPM) make efficient use of these different types of demographic data by jointly analysing them. This chapter discusses the advantages and the possibilities offered by this integrated approach. It describes the different steps required to build an IPM and illustrates the usefulness of this approach using two case studies. The first case study is a short-lived bird species, the blue tit, taking advantage of different data sources collected in a Dutch population to highlight how an integrated analysis might help to obtain a comprehensive picture of its dynamics. This IPM also assesses whether and how beech crop size might influence vital rates. The second case study is an invasive plant species, the common ragweed. The chapter illustrates how seedling data, plant data, and seed bank data could be analysed simultaneously to estimate key vital rates such as the probability that a seedling survives up to flowering.