Introduction Cooking at home is associated with better diet quality. This study examined the frequency of home-cooked dinners versus eating out in relation to the Healthy Eating Index (HEI), and food expenditures. Methods The Seattle Obesity Study used a stratified random sample of 437 King County adults. In-person computer-assisted interviews collected sociodemographic and behavioral data during 2011–2013. HEI-2010 and 2005 were computed using Food Frequency Questionnaires. Multivariable regression analyses, conducted in 2015, examined associations among HEI scores, food expenditures, and frequency of cooking at home versus eating out variables. Results Frequent home-cooked dinners were associated with being married, unemployed, larger households, presence of children aged <12 years, and lower frequency of eating out, but unrelated to education or income. In adjusted models, frequent at-home cooking was associated with higher HEI-2010 (β=7.4, p <0.001), whereas frequent eating out was associated with lower HEI-2010 (β= –6.6, p <0.001). Frequent home cooking was linked with reduced per capita food expenditures overall ($330/month among low vs $273/month among high cooking group, p <0.001), and reduced away-from-home expenditures ($133 and $65, respectively), without any significant increase in at-home food expenditures. However, frequent eating out was associated with significantly higher per capita food expenditures overall ($261 in low vs $364 among high eating out group, p =0.001), and higher away-from-home expenditures. Conclusions Home-cooked dinners were associated with greater dietary guideline compliance, without significant increase in food expenditures. By contrast, frequent eating out was associated with higher expenditures and lower compliance. Home cooking may be a component of nutrition resilience.