This presentation reports on selected results of Swiss primary and secondary teachers’ beliefs and concerns about using inquiry-based learning strategies in mathematics and science education. As part of an international baseline study, a survey was conducted in 2011 in Geneva, and the responses of 162 science and mathematics teachers were collected, half at primary and half at secondary level. The analysis of teachers’ responses illustrates that Geneva teachers feel less compelled to implement more IBL in their lessons than their colleagues surveyed in the other countries, because they believe that they already use IBL practices. Even though they do not think that IBL requires students to have extensive content knowledge, they are skeptical about IBL being helpful for overcoming students’ learning problems. Some differences appeared among the different groups: primary teachers asked for support to integrate IBL, considered the lack of teaching material and resources and worried about students' discipline in IBL-type lessons, whilst secondary teachers were particularly concerned with time limitations and curricular demands. The authors will discuss these and other results in the light of qualitative results from the Professional Development evaluations.