Doubled-up Latinx youth experience many daily challenges associated with ethnic minority status and residential instability. Doubled-up youth share housing with noncustodial caregivers such as friends and/or extended family members primarily because of economic hardship and a breakdown in available parental support. Using data from baseline and 10 days of twice-a-day surveys, this study examined how in-school positive experiences, familism (i.e., a perspective that gives precedence to the family), and ethnic identity (i.e., affirmation, exploration, and resolution) influence after school positive (e.g., feeling joyful/happy) and negative (e.g., feeling stressed/anxious) affect among doubled-up Latinx youth (70% female; M age = 16.5). Results indicate that in-school positive experiences were associated with more after school positive affect and less after school negative affect. In addition, youth with higher levels of familism reported experiencing less after school negative affect. However, gender moderated the relation of ethnic identity exploration and experiences of after school positive affect. Specifically, females with higher levels of ethnic identity exploration reported relatively lower levels of after school positive affect compared with males. Overall, study findings highlight the importance of both person-level and varying contextual influences on the affective lives of doubled-up Latinx youth. K E Y W O R D S daily diary design, doubled-up youth, familism, Latinx 1 | INTRODUCTION Approximately 2.5 million youth in the USA are homeless according to the National Center for Homeless Education (NCHE; 2016), which highlights a pervasive inequality that merits increased attention and intervention. According to the NCHE, the majority of homeless youth (75%) share housing with a series of friends and/or extended family members because of economic hardship. Such youth are referred to as "doubled-up" and experience environmental instability while relying on others to meet their basic needs. Although doubled-up youth are homeless, they are often not included in researchers' conceptions of homelessness or research on homelessness, because they do not fit typical stereotypes of homelessness such as living on the street (see e.g., Toolis & Hammack, 2015; Torino & Sisselman-Borgia, 2017). Being doubled-up, like being homeless, also places students at risk for being exposed to myriad environmental threats, as well as being victimized, exploited, and having negative long-term life outcomes