The main aim of this research is to contribute to the formative assessment, assessment as learning, assessment for learning and assessment of learning research area. Assessment as learning and assessment for learning are approaches to formative assessment included in the concept of assessment proposed by the School for Life programme implemented in Croatian schools in September 2019. Other than those two approaches, the assessment of learning approach, which refers to summative assessment, is also included. These terms are widely represented, have been developed and researched by Anglo-American experts on the subject. Croatian docimology is in its infancy with the use of the terms "assessment as learning", "assessment for learning" and "assessment of learning", although the term "formative assessment" has been elaborated in the Croatian docimological literature. These approaches of assessment have only just been introduced into the Croatian education system, although they include some methods that teachers have been using on their own accord. For the successful implementation of the proposed assessment concept, it is important to take into account the distinctive characteristics of the implementation, i.e. the context of the Croatian education system. Two fundamental determinants which are important for the success of the implementation are the willingness and interest of teachers to change the assessment and resources (primarily time and materials). To determine whether teachers are ready for changes in assessment, (1) their understanding of assessment, (2) competence for assessment within the proposed concept, (3) experience in implementing the proposed assessment approaches and satisfaction with the proposed assessment concept were examined. To test these parameters, the chosen methodology was a qualitative one. The chosen research method was a semi-structured interview, with the basic determinants being: understanding, competence, implementation and satisfaction. The interview was conducted with 10 teachers (two subject teachers, two primary school teachers, three high school teachers and three vocational school teachers). Nine participants were female and one male, all of whom have between 11 and 29 years of teaching experience. In conclusion, the collected data showed that research participants are ready for changes in assessment and show interest in improving formative assessment. However, they lack time for quality implementation of the proposed approaches to assessment. Research participants believe that they are at a satisfactory level of competence for the implementation of the proposed concept of assessment, but they believe they still need to improve their assessment skills. They are implementing the proposed approaches to assessment and are satisfied with the concept of assessment. They claim that it takes time for their improvement in assessing and implementing the proposed approaches to better quality assessment. Given the results of the research, it can be concluded that a more comprehensive evaluation of the assessment reform is needed. In addition, there is a need for further professional development of teachers in the field of assessment, as well as the provision of materials and time resources that will enable quality implementation of the proposed concept of assessment.