["Journal for the Scientific Study of Religion, Volume 65, Issue 1, Page 29-48, March 2026. ", "\nABSTRACT\nThis article analyzes changes in religiosity of the migrant–origin population in Spain. Using data from the Spanish General Social Survey (ESGE) from four different years between 2013 and 2023, we compare people with migrant background with respect to the native‐born population in terms of religious affiliation (vs. being non‐affiliated) and service attendance, and examine trends in immigrant religiosity over time. We study changes in two ways: For the foreign‐born first generation, we analyze religiosity in relation to their length of stay in Spain, and we study intergenerational change by comparing levels of religiosity of the local‐born second generation to those of the first generation. Our findings support neo‐assimilation theory, that is, with a longer duration of stay, immigrants and their descendants become more similar to the secularizing Spanish environment. The only exception to the common trend is an increase in religious service attendance among first‐generation Eastern European migrants.\n"]