In 1966, after the founding of the RTVE Symphony Orchestra in Madrid, Ros-Marbà won a conducting competition and was named the Principal Conductor of this orchestra. In 1967, he became Principal Conductor of the Orquestra Ciutat de Barcelona, until 1978, and again from 1981 to 1986. In 1978 he was named Music Director of the Spanish National Orchestra. From 1979-1986, he led the Netherlands Chamber Orchestra as Principal Conductor.