The Modern Era Reanalysis (ModE-RA) is a global monthly paleo-reanalysis covering the period from 1421 to 2008. It uses an offline data assimilation approach, blending ensemble atmospheric model simulations and observations to reconstruct past climate fields. The early period relies on natural proxies and documentary data, while instrumental measurements are assimilated from the 17th century onwards. The impact of each observation is stored in an observation feedback archive, providing additional information on the input data. ModE-RA includes estimates of key climate fields and a reconstruction, ModE-RAclim, which helps disentangle the role of observations and model forcings. ModE-RA is well-suited for studying intra-annual to multi-decadal climate variability and analyzing past extreme climate events. The dataset is evaluated against independent time series, gridded instrumental observations, and other climate reconstructions, showing good agreement with 20th-century gridded monthly products. The evaluation also confirms the high quality of ModE-RA, particularly in regions with sparse observational data, such as South America and Africa.The Modern Era Reanalysis (ModE-RA) is a global monthly paleo-reanalysis covering the period from 1421 to 2008. It uses an offline data assimilation approach, blending ensemble atmospheric model simulations and observations to reconstruct past climate fields. The early period relies on natural proxies and documentary data, while instrumental measurements are assimilated from the 17th century onwards. The impact of each observation is stored in an observation feedback archive, providing additional information on the input data. ModE-RA includes estimates of key climate fields and a reconstruction, ModE-RAclim, which helps disentangle the role of observations and model forcings. ModE-RA is well-suited for studying intra-annual to multi-decadal climate variability and analyzing past extreme climate events. The dataset is evaluated against independent time series, gridded instrumental observations, and other climate reconstructions, showing good agreement with 20th-century gridded monthly products. The evaluation also confirms the high quality of ModE-RA, particularly in regions with sparse observational data, such as South America and Africa.