key ECI works off 7 Key Principles for early intervention:

Children learn best through everyday experiences and interactions with familiar people in familiar contexts.
All families with the necessary supports and resources can enhance their child's learning.
The primary role of service providers are to work directly with and support family members and caregivers in a child's life.
The early intervention process from initial contact through transition must be dynamic and individualized to reflect the child and family member's preferences, learning styles and cultural beliefs.
Individualized Family Service Plan (IFSP) outcomes must be functional and based on child and family's needs and priorities.
The family's priorities, needs and interests are addressed by a primary provider who represents and receives team and community support.
Interventions are based on explicit principles, validated practices, best available research and relevant laws and regulations.

The key aspect in all 7 principles of early intervention is: the family.