Paraprofessionals are high-level library support personnel. Also called support staff or support assistants.
Unlike librarians, they do not usually have an MLS degree.They may receive their training through college as Library Technicians or through on-the-job training. The labels "paraprofessional" and "semi-professional" can be criticized as sounding derogatory, as can requiring a library degree for positions that seasoned support staff are qualified to hold. Along with student workers and volunteers, paraprofessionals do the bulk of operations work in a library. Paraprofessionals with technical training may earn more than librarians. 
As with similar groups of educational achievement in other professions (doctors and nurses, lawyers and paralegals, officers and enlisted soldiers, etc.), the relationship between librarians and support staff can vary greatly. Some libraries have unionized staff support, which may add or detract to the level of collegiality.