This article is the fifth in a series of eight articles that form a special issue on Family-Centered Early Intervention (FCEI) for children who are deaf or hard of hearing (DHH) and their families, known as FCEI-DHH. The 10 FCEI-DHH Principles are organized into three sections: (a) Foundation Principles, (b) Support Principles, and (c) Structure Principles. These principles guide FCEI-DHH for children who are DHH and their families. This article focuses on the Foundation Principles (Principles 1 and 2). The Foundation Principles emphasize the essential elements of ensuring that families with children who are DHH can access early intervention (EI) and other appropriate supports, as well as highlight the need for EI that is family-centered. Principle 1 emphasizes early, timely, and equitable provision of supports following identification that a child is DHH. Early identification should be linked to early, timely, and equitable access to supports and interventions. Early intervention is crucial for preventing delayed access to language and communication, and maximizing early stimulation opportunities for children who are DHH. The World Health Organization (WHO) recommends newborn hearing screening and early intervention as essential for children who are DHH. The WHO also emphasizes the importance of early intervention as early as possible after identification, considering the communication needs and preferences of the family and available resources. Timely provision of supports is essential, with benchmarks such as the "1–3–6 plan" emphasizing hearing screening by 1 month of age, diagnostic audiologic assessment by 3 months, and enrollment in EI no later than 6 months. Emerging evidence supports accelerated timelines, such as the "1–2–3" plan. However, these timelines may not be achievable in all countries due to lack of early identification programs. In such cases, programs should aim to serve children and families as early as possible following identification. Equitable provision of supports ensures that all families have the same opportunities, regardless of race/ethnicity, class, gender, language, religion, disability, or other differences. Equity involves not just access but also the quality of what is provided. FCEI-DHH programs should proactively establish mechanisms to limit the impact of challenges resulting from program limitations, family circumstances, geographical location, and socioeconomic/sociopolitical national context. Principle 2 focuses on family-EI Provider relationships, emphasizing partnerships, engagement, capacity-building, and reflection. Family-EI Provider partnerships are supportive contexts for fostering the self-efficacy and capacity of families to nurture their child. These partnerships enhance EI Providers' understanding and ability to effectively support families. Effective partnerships involve mutual trust, respect, and clear communication. Family-EI Provider partnerships benefit from relational practices and participatory practices, including family engagement, informed decision-making, and incorporation of family needs and priorities. Engagement in FCEI-DHH varies across families and contexts. Family involvement is stronglyThis article is the fifth in a series of eight articles that form a special issue on Family-Centered Early Intervention (FCEI) for children who are deaf or hard of hearing (DHH) and their families, known as FCEI-DHH. The 10 FCEI-DHH Principles are organized into three sections: (a) Foundation Principles, (b) Support Principles, and (c) Structure Principles. These principles guide FCEI-DHH for children who are DHH and their families. This article focuses on the Foundation Principles (Principles 1 and 2). The Foundation Principles emphasize the essential elements of ensuring that families with children who are DHH can access early intervention (EI) and other appropriate supports, as well as highlight the need for EI that is family-centered. Principle 1 emphasizes early, timely, and equitable provision of supports following identification that a child is DHH. Early identification should be linked to early, timely, and equitable access to supports and interventions. Early intervention is crucial for preventing delayed access to language and communication, and maximizing early stimulation opportunities for children who are DHH. The World Health Organization (WHO) recommends newborn hearing screening and early intervention as essential for children who are DHH. The WHO also emphasizes the importance of early intervention as early as possible after identification, considering the communication needs and preferences of the family and available resources. Timely provision of supports is essential, with benchmarks such as the "1–3–6 plan" emphasizing hearing screening by 1 month of age, diagnostic audiologic assessment by 3 months, and enrollment in EI no later than 6 months. Emerging evidence supports accelerated timelines, such as the "1–2–3" plan. However, these timelines may not be achievable in all countries due to lack of early identification programs. In such cases, programs should aim to serve children and families as early as possible following identification. Equitable provision of supports ensures that all families have the same opportunities, regardless of race/ethnicity, class, gender, language, religion, disability, or other differences. Equity involves not just access but also the quality of what is provided. FCEI-DHH programs should proactively establish mechanisms to limit the impact of challenges resulting from program limitations, family circumstances, geographical location, and socioeconomic/sociopolitical national context. Principle 2 focuses on family-EI Provider relationships, emphasizing partnerships, engagement, capacity-building, and reflection. Family-EI Provider partnerships are supportive contexts for fostering the self-efficacy and capacity of families to nurture their child. These partnerships enhance EI Providers' understanding and ability to effectively support families. Effective partnerships involve mutual trust, respect, and clear communication. Family-EI Provider partnerships benefit from relational practices and participatory practices, including family engagement, informed decision-making, and incorporation of family needs and priorities. Engagement in FCEI-DHH varies across families and contexts. Family involvement is strongly