OBJECTIVE: A community-based participatory nutrition promotion (CPNP) programme, involving a 2-week group nutrition session, attempted to improve child feeding and hygiene. The implementation, utilization and influence of the CPNP programme were examined by programme impact pathway (PIP) analysis. DESIGN: Five CPNP programme components were evaluated: (i) degree of implementation; (ii) participants' perception of the nutrition sessions; (iii) participants' message recall; (iv) utilization of feeding and hygiene practices at early programme stage; and (v) participants' engagement in other programmes. SETTING: Habro and Melka Bello districts, Ethiopia. SUBJECTS: Records of 372 nutrition sessions, as part of a cluster-randomized trial, among mothers (n 876 in intervention area, n 914 in control area) from a household survey and CPNP participants (n 197) from a recall survey. RESULTS: Overall, most activities related to nutrition sessions were successfully operated with high fidelity (>90 %), but a few elements of the protocol were only moderately achieved. The recall survey among participants showed a positive perception of the sessions (~90 %) and a moderate level of message recall (~65 %). The household survey found that the CPNP participants had higher minimum dietary diversity at the early stage (34·0 v. 19·9 %, P=0·01) and a higher involvement in the Essential Nutrition Action (ENA) programme over a year of follow-up (28·2 v. 18·3 %; P<0·0001) compared with non-participants within the intervention area. CONCLUSIONS: Our PIP analysis suggests that CPNP was feasibly implemented, promoted a sustained utilization of proper feeding behaviours, and enhanced participation in the existing ENA programme. These findings provide a possible explanation to understanding CPNP's effectiveness.