This study evaluates Venezuela's National System of Child and Youth Orchestras, better known as "El Sistema".

The randomized control trial was conducted in 16 music centers in Venezuela between May 2012 and November 2013, with a population of 6-14 year olds seeking entry to the program. During an application period (May-July 2012), 2,603 guardians (the experimental cluster) applied on behalf of 2,999 6-14 year olds. Approximately half of the guardians were randomly offered early admission in September 2012, with the rest offered admission in September 2013. Baseline and follow-up data were collected on outcomes which will be explored for full-group and specific sub-groups (children with less educated mothers, and boys or girls exposed to violence).

Inclusion criteria:

• Excess demand in 5 geographic areas: 24 music centers across the 5 states were identified as the experimental sites based on the likelihood of having excess demand by families in the 2012-13 academic year.
• Apply protocol: Experimental sites agreed to accept written applications from guardians between May 7 and July 8, 2012 (without informing guardians of admission decisions until after randomization). Directors consented to participate in the experiment and received training in the experimental protocol. Children were eligible to apply if they would be 6 to 14 years old on September 1, 2012. Sites received applications from 2,603 guardians on behalf of 2,999 children.

Exclusion criteria:

• Music center level: Two sites were excluded because their directors declined to follow the experimental protocol, and six were excluded because of insufficient demand to carry out randomized experiment.
• Child/guardian level: By prior agreement, each site director could award early admission to a small number of applicants (no more than 5% of positions). In eight sites, 85 children (of 74 guardians) were excluded from the study because they entered through these positions allotted to site directors. Children were also lost from study if parental consent and child assent not given.