Practicum is one of the important processes preservice teachers engage in during their preparation. In this study, we explored school-based mentors’ (SBMs) assessment and feedback comments of preservice teachers’ (PSTs) teaching ability during practicum. We aimed specifically to assess mentors’ judgment comments on lesson teaching activities during a six-week practicum in diverse teaching contexts. For a deeper understanding of the judgment comments, we invoked two theories; the cultural historical activity theory (CHAT) and the social judgment theory (SJT). We collected and analysed data through qualitative and quantitative methods. Our findings show that mentors’ judgment comments vary across and within contexts. That is, assessment comments differed between individual mentors within and across contexts in terms of what assessors focused on or about the aspects of the criteria that were mentioned in their comments. As for the quality (e.g. comprehensiveness, accuracy or appropriateness) of the judgment comments (as feedback), mentors were not comprehensive in their comments and their reference to criteria was limited and in some cases inconsistent. In some instances, comments were inappropriate; they did not add any formative value or relate to the criteria. Generally, mentors’ feedback comments lacked usefulness to the university educator’s and preservice teacher’s formative purposes. In conclusion, the study highlights the importance of quality and equity of and in assessment, especially of the same cohort in diverse teaching contexts. That is, there is the need for an assessment instrument that would ensure that most aspects of the criteria are comprehensively assessed and commented on, especially for formative purposes. DOI: 10.5901/mjss.2014.v5n27p821