Purpose The purpose of this paper is to review the existing literature on the critical success factors (CSFs) of various continuous improvement (CI) like total quality management (TQM), Lean, Six Sigma and Lean Six Sigma (LSS), and perform a content analysis (CA) leading to an agenda for future research. Design/methodology/approach CA is based on literature review of 41 papers published in peer-reviewed scholarly journals. A four-stage methodology is used by the authors, with Stage 1 featuring relevant material collection; Stage 2 presenting a descriptive analysis; Stage 3 outlining the category selection; and Stage 4 featuring the material evaluation using clustering and Pareto analysis. Findings The CA revealed various research implications and directions for the future. The number of studies in the literature regarding CSF assessment is found to be far from substantial while compared to CI implementation. Assessment methodologies developed have been ranging from qualitative to quantitative models. Key gaps were identified and directions for CSF assessment are proposed which requires further validation. Research limitations/implications Only articles that appeared in peer-reviewed journals were analyzed; conference papers, reports, manuals and white papers from practice were excluded. Another limitation of the paper would be the scope of CA limited to four CI constructs – TQM, Lean, Six Sigma and LSS. Research implications indicate that the future studies in this domain would be intensive toward analyzing the vital CSFs for enterprise organizational excellence and not merely process excellence. Practical implications This review study can serve as a resource for both researchers and practitioners to understand the importance of CSFs and positioning CSFs for the successful implementation of CI programs. Originality/value The CA on the existing literature on CSFs for CI presents a unique, systematic effort to identify an agenda for future research. This study is the apparently the first of its kind on CSF assessment.