The aim of this article is to promote discussion and professional development around the topic of learning difficulties in mathematics, particularly as these pertain to teaching and learning in the middle school years. The article has three sections. In the first section, a review of literature about learning difficulties (LD) in mathematics is presented. Definitional issues are discussed, key underlying causes of LD in mathematics are highlighted and common "learner characteristics" of middle-years students with LD in mathematics are identified. The second part of the article is an overview of a responsive intervention currently being developed to support middle-years students with LD in mathematics. This section describes the implementation of the "QuickSmart" mathematics intervention with 42 participating students and 12 comparison students enrolled in five schools from a rural area of New South Wales. The results of pre-intervention and post-intervention assessments, using both standardised and achievement-based measures are reported. The findings indicate that the "QuickSmart" intervention approach improved students' mathematical knowledge, skills and understandings. In the third section of the article research-validated, curriculum-relevant strategies from the "QuickSmart" mathematics program are described. (Contains 3 tables and 2 figures.)