STEAM education postulates integrated problem-solving-based learning of its disciplines. Although positive results are being reported, there are some difficulties with its implementation. The purpose of this research is to analyze the conceptions and attitudes of Early Childhood and Primary School teachers in Spain towards this educational approach, as well as to determine the initial relationship with their training and experience. A multiple case study with 11 teachers was conducted using a reflection protocol, a photo-elicitation, and a semi-structured interview. All teachers presented an integrated profile. Although they explicitly acknowledged cognitive, affective, and logistical obstacles, a positive relationship was detected between their level of training, experience in STEAM education, and conception of STEAM. Based on this evidence, some recommendations are proposed to optimize the conceptions of the STEAM approach and the usual practices of the teaching staff.