This paper investigates factors that influence the extent of corporate mandatory disclosure practices in New Zealand over a three‐year period. Researcher‐created disclosure‐scoring templates consisting of mandated information items from three regulatory sources were used to derive indexes of disclosure in financial annual reports of the sample companies. Regression analysis suggests that company age is the most critical factor in explaining the extent of mandatory disclosure practices of the companies. The results also indicate that company size, liquidity, profitability, existence of audit committee, and auditor‐type are consistently positively related to the extent of corporate mandatory disclosure. Further research opportunities are suggested.