The aim of this case-study was to understand how chemistry teachers experience their work in diverse classes where the needs of differentiated teaching practices are constantly growing. The deeper intention was to perceive new information in order to develop supportive methods that could better correspond to teachers' reality. Eight voluntary Finnish secondary school chemistry teachers participated in semi-structured interviews. Four categorial distinctions for successful chemistry teaching were found according to their beliefs: 1) to have more support and resources, 2) to be able to recognize students' problems, 3) to use supportive materials and methods, and 4) to connect theory and practice with inspiring and meaningful activities. This study presents new insights about teachers' beliefs of diversity and what is needed for successful chemistry teaching. Directions for further research and practices are also suggested.