1970s - Today: IMCS and IYCS
In the 1970s, IMCS would grow closer to IYCS. This would be both enriching and changeling at the same time. IMCS and IYCS would establish joint regions in Latin America, Europe and the Middle East. In 1978, IMCS held it's IFA in conjunction with IYCS' World Council (WC) in Valladolid, Spain. There the two movements examined their relationship, taking into consideration their commonalities and differences. As part of this event, the two adopted the IMCS-IYCS Common Pastoral Project for common work in the universities.

As part of this new relationship, the IMCS International Secretariat would leave its long time home in Fribourg, and its common office with ICMICA to share space in Paris with IYCS.

IMCS and IYCS would continue to use this model of common study sessions and separate IFAs and WCs until 1991. At the IFA and WC in 1991 in Hong Kong IMCS decided to replace the IFA with an International Committee. IYCS decided to use the International Committee (IC) as its alternate to the World Council.

In 1995, IMCS and IYCS organized the first International Committees (IC) in Yamoussoukro, Ivory Coast. As with the previous system, the ICs would have common study sessions and separate statutory sessions.

In August of 1999, IMCS and IYCS held the second ICs in Strasborg, France and adopted a Protocol of Collaboration between IYCS and IMCS. In August of 2003, IMCS and IYCS held the third ICs in Barcelona, Spain with the theme of "Students Ready for Change." In July of 2007, IMCS held the fourth IC in Kuala Lumpur, Malaysia with the theme of "Empowering Student Action for Dialogue and Peace."