Recruiting participants through gatekeepers has been widely discussed in qualitative research. However, when a sampling frame is not available, surveying through gatekeepers can also be important for quantitative studies. We used three sampling methods to survey guardians of University students: (a) a gatekeeper variant of the time-space sampling, (b) a direct postal survey to a random sample of guardians' addresses, and (c) a phone survey of the general population. The gatekeeper survey was the most efficient, but yielded a skewed sample. Albeit skewed, the gatekeeper sample yielded the same responses as the random sample, on five theoretically important scales (N = 29 questions). In-depth personal interviews and online semi-structured questionnaires with guardians and students revealed a two-way gatekeeping mechanism within families, regulating guardians' participation in the study. We discuss the indispensable contribution of qualitative data in our study and provide methodological suggestions for practitioners.