Purpose　In　this　study,　the　authors　employ　an　intellectual-capital　based　view　of　the　firm　to　examine　the　relationship　between　three　bundles　of　human　resource　development　(HRD)　practices　(i.e.　developmental,　constructive　and　collaborative　HRD　practices),　three　dimensions　of　intellectual　capital　(i.e.　human　capital,　organizational　capital　and　social　capital),　and　organizational　performance　improvements.　Specifically,　the　authors　investigate　the　mediating　role　of　intellectual　capital　in　the　relationship　between　HRD　practices　and　changes　in　organizational　performance.　Design/methodology/approach　The　authors　randomly　distributed　questionnaires　to　1,000　HR　executives　of　Taiwanese　firms　to　assess　the　firms＇　HRD　practices　and　intellectual　capital.　Firm　performance　data　in　terms　of　return　on　assets　(ROA)　were　obtained　from　the　Taiwan　Economic　Journal　(TEJ).　To　test　the　model,　the　authors　used　the　longitudinal　data　over　three　years　from　213　firms　in　Taiwan.　Findings　The　results　show　that　human　capital　and　social　capital　mediate　the　relationship　between　HRD　practices　(i.e.　developmental　and　collaborative　HRD　practices)　and　organizational　performance　improvements　in　terms　of　return-on-assets　growth.　Originality/value　This　study　adds　to　the　empirical　evidence　regarding　whether　or　not　investment　in　HRD　practices　can　lead　to　positive　changes　in　financial　performance.