Internationally, support staff with limited teacher training (Teaching Assistants [TA]) are hired to support the mainstream education of children with Special Educational Needs and/or Disabilities (SEND). Meanwhile, teachers instruct the whole class. Although TAs might help children with significant difficulties participating in the classwork (complex SEND), children with milder needs could overly rely on TAs' support to complete classroom tasks, ultimately compromising their thinking and learning. This study was conducted in an insufficiently examined and unique context (Italy), providing support staff (Support Teachers [ST]) with special- and mainstream-pedagogy training and overlapping whole-class responsibilities with classroom teachers. Drawing from classroom observations of an ST and interviews with 31 other STs in Italian primary schools, the findings illustrate that the STs primarily instructed children with SEND despite their level of need. Rarely did they collaborate with teachers in whole-class instruction. The interviewed STs widely associated their 'specialist' role with the broader perceptions that STs are better prepared for SEND support due to their special education training not available to teachers. STs' professional characteristics therefore create imperfect conditions seen elsewhere for the education of children with (mild) SEND. The findings have significant implications for re-thinking ST professional characteristics.