OBJECTIVE: We address the crucial and challenging task of anticipating the resources needed to recruit eligible participants for research. We provide our analysis of various recruitment strategies and their cost-effectiveness in our experience in enrolling 610 women for an observational study on ovulation. METHODS: We assess the cost-effectiveness and success of multiple recruitment strategies we employed and provide the estimated cost of labor and materials for each. At enrollment, all participants were asked an open-ended question about how they learned about the study. No financial compensation was provided, but participants received personal hormonal analysis results on completion. RESULTS: Of the 610 enrolled women, 552 provided information on how they learned about the study. The total cost of recruitment was $7645.11, which includes 183 staff hours. The average recruitment cost per participant was $12.53 (ranging from $0 to $118.63). The two methods with the lowest total costs resulted in enrollment of 48% of the recruitment goal using only 0.3% of the budget. In contrast, the two methods with the highest total costs produced 13% of the participants needed but consumed over 72% of the budget. CONCLUSIONS: Low-cost methods are a viable, practical source for attracting healthy women for observational research. Investigators are encouraged to track sources of recruitment and analyze their data at regular intervals during the recruitment phase. Sharing comprehensive recruitment data will assist other researchers to better estimate the resources needed to meet their enrollment goal, leading to more efficient use of time and funding.