Natural selection has equipped with decision rules that allow them to behave in flexible, but adaptive, ways (Kushnick 2011; Voland 1998; Winterhalder & Smith 2000). Decision rules are central to most behavioral ecological explanations of behavioral diversity, taking the form of “in context x do a; in context y switch to b” (Winterhalder & Smith 2000:54). The use of correlational (or observational) methods has hampered the study of decision rules because one cannot eliminate confounding and confidently ascribe causality in the absence of experimental methods. In this study, an experimental vignette study design will be used to illuminate the factors that play into maternal investment decisions. Borrowing from Voland’s (1998) list of factors that effect the costs and benefits of childcare strategies, we will present respondents with hypothetical childcare scenarios and ask what the hypothetical woman in the scenario would do. The design includes five variables of two levels each, totaling 32 vignettes in all. Each respondent will be faced with just eight of them selected using a confounded factorial experimental design (which allows all main and 1st-order interaction effects to be estimated without confounding) (Atzmuller & Steiner 2010). After each vignette, the respondent is then asked four questions with Likert scale responses. The questions were designed to capture the full range of childcare scenarios: low cost/low benefit, low cost/high benefit, high cost/low benefit, and high cost/high benefit. Responses will be analyzed using multilevel linear models.