Dr. Guillen has participated in many professional ensembles, including the Honduras National Symphony Orchestra, Honduras Philharmonic Orchestra, Pensacola Symphony Orchestra, and Mobile Symphony Orchestra. He has also been Principal Second Violin for the Gulf Coast Symphony Orchestra in Mississippi, The Lubbock Symphony Orchestra in Texas, and The Symphony of the Southeast Texas (current position). Other professional groups include the Magnolia Chamber Orchestra, The Zachow Consort and Players, The Houston Camerata, and the Vivaldi String Quintet.
Dr. Guillen has also participated as guest artist and clinician at the VII International Music Festival in Medellin Colombia, the Victoria Bach Festival, the Quartz Mountain Music Festival in Oklahoma, the Magnolia Chamber Orchestra Summer Fest in Mississippi, and the Masterworks Series in Maryland. Other apprearances include festivals in San Jose, Costa Rica, Masterworks Music Festival in New York, Round Top Music Festival in Texas, and The International Music Academy in Plzen, Czech Republic.
Dr. Guillen has also been a member of the Youth Orchestra of the Americas (YOA), participating in the tours of 2003 and 2012 around the Americas giving concerts in nine different countries. In 2012 Mr. Guillen was selected to be a member of the first generation of the Global Leaders Program (GLP) of the Youth Orchestra of the Americas. In 2013 he received a fellowship from the GLP to continue developing educational projects in Honduras. As a member of the GLP, Dr. Guillen participated in educational missions to El Salvador, Chicago, and Honduras working with young musicians and performing with youth orchestras from the regions, including the Chicago Civic Orchestra. As a Global Leaders graduate, Mr. Guillen served as a mentor for the third generation of YOA leaders.
In 2007 Mr. Guillen won Second Place at the MTNA concerto competition in Jackson, Mississippi and in 2010 was the winner of the Texas Tech Concerto Competition. Dr. Guillen has also performed as a soloist with the Honduras Philharmonic Orchestra, Texas Tech Symphony Orchestra, the Magnolia Chamber Orchestra, The UNAH Chamber Orchestra, and the Orquesta Joven Sinfonica of Colombia. He is currently a member of the Suzuki Association of the Americas, keeps a private studio in Houston, and works as a voluntary member of the Honduras Arts Foundation (Farecoh).
Dr. Guillen is currently the Lead String Teacher of the Coda Program, an “El Sistema” based initiative by the Houston Youth Symphony. He is the Co-founder and Executive Director of the “Encuentro Anual de Cuerdas,” a String Festival that takes place in Tegucigalpa, Honduras. Mr. Guillen is married to Venezuelan cellist Mayara Velasquez.