Children's time use is a complex developmental phenomenon in need of a more in-depth, detailed understanding. The present study aimed to provide a comprehensive description of children's everyday lives in middle childhood and examine how different portfolios and patterns of daily activities occurring at home, school, and community are influenced by multilevel ecological factors. Based on cross-sectional, multi-informant data from a sample of Portuguese 3rd and 4th graders (n = 209), this research expands previous literature by providing a mixture of variable- and person-centered analytical approaches to children's time use. Findings indicate that children's everyday lives are characterized by a diversity of participation portfolios which embody multidimensional, heterogeneous, and qualitatively distinct participation patterns. A total of five different time use clusters were found: "less-active studious", "highly-engaged players", "less-involved after-schoolers", "highly-active homebodies", and "sedentary home screeners". Both portfolios and patterns of activities significantly varied as a function of child characteristics, parental education, family functioning and culture, and the environment quality of activity settings. Variations in ecological affordances and constraints may represent different levels of exposure to developmental opportunities. An ecological developmental perspective of children's time use is necessary and useful to enlighten how families, schools, and communities can positively influence children's lives and effectively support their well-being and growth.